Also, if you were expecting to get advice on which one to buy you may have come to the wrong place. What I will expound on below is what I think a perfect eBook reader ought to be. I may give examples of little bits that some already available have done right (and link to them, too), but you will find that there isn't one good enough for me, yet.
Before I even start on what a good (perfect, remember!) eReader has to have, let me tell you what I think are good sides of eReaders, but also of proper, real, paper books.
I may be old fashioned, but there is still something really nice about holding a book, flipping its pages, and seeing it sit on the shelf. Also, for quickly finding your way around, no computer yet beats a good index, and a flick through the pages. Even just flicking through the pages and doing an "eyeball search" often beats a digital search feature. Then, if you are that way inclined (and do not expect to sell your books), scribbling little notes in the margins is something that just feels good, right, and proper, as does some judicious highlighting or (better) underlining. Oh, and you can easily give books as gifts or lend them, and the process feels good. How do you go about nicely wrapping an eBook?
These take no space at all! OK, you do have your eReader, and it may take memory cards, but that's all physical volume you'll ever need. If you're mostly into books that consist of words (as opposed to illustrations) then even today you can cram an enormous library either on the eReader itself, or on a tiny little (physically tiny little) memory card. Certainly an amount that you'd rarely see outside a major national library. Also, your eReader is bound to be rather slim, unlike some real books (think collected writings of Darwin, which I gave up on reading as it hurt my hands, arms, and chest when I tried reading it in bed). With ubiquitous Internet access these days, you'll also likely be able to grab the exact book you want regardless of where you are -- no more wasting money on silly holiday reads when you forget to bring something better with you.
Given the two paragraphs above, I somehow think I'll continue buying real books even when I switch all (or most) of my reading to eBooks. I know I'm a dinosaur in that respect (and I still think 12" vinyl records have more "soul" than CDs, and especially digital downloads). But I also think that a proper (ideal, perfect) eReader is still some time away. Let me tell you why.
Oh, when I say books, I also mean magazines, newspapers, etc. I'll say books, and you just think printed matter. OK?
This is not a problem any more, it seems. Current crop of eReaders come in a decent variety of sizes, most of which are good enough for the purpose. Unfortunately, it seems that one problem that will stay unsolved for a long time is that different books call for different form factors. Possibly when flexible, foldable screens become ubiquitous this will be solved, too, but I don't see it happening any-time-soon(tm) so I won't add changeable form factor to the must-have list for a perfect eReader.
So what is my perfect form factor (or rather, form factors)? Personally, I think I'll need two. if you are a fan of broadsheet newspapers then you may have to add a third. My two ideal form factors are A5 (or a tad smaller), and A6 (or a tad smaller). The former to be used at home, or elsewhere where we can more easily make ourselves comfortable, and the latter for commuting or other uncomfortable or cramped situations where it may be beneficial to be able to use just a palm of your hand to hold and operate the eReader.
For magazines and newspapers I'd go for A4 (or a bit smaller) size, but I think I could live without it, or the publishers could think of clever ways to put their fare into A5 size. One idea for this would be to have a foldable A5 eReader that opens like a real book into an A4 landscape affair. I wouldn't like it to be able to be rotate to portrait, but that's negotiable. What it would have to be able to do is to fold neatly into its smaller size, and used as if it's A5 size, one sided thing only.
Whoever thinks they have an idea how to create a single eReader that could fold away into A6, A5, and A4 sizes, and still be of decent volume and build quality, will probably be rich in a few years' (or decades') time. If you'd like to run your idea past me, replies on a postcard please (or in comments, below).
In conclusion, I don't think the current crop of eReaders have got it wrong in this respect. It's just I may need to get more than one. With even the prices going down nicely, I don't think we have a problem here.
Right now I think this is the area where the readers have their biggest problem right now. This is tightly related to battery life, too, but I'll tackle that below. Most (all?) eReaders now use eInk-type screens. They are great if you want your screen to look as much as possible like a piece of paper. And invariably they do. The problems, however, are I think horrible.
One, they do not have any backlight, so reading in poor light conditions is a no-go. Here I don't (only) mean reading in bed, with lights off so your SO can sleep. I also think of places like poorly lit bus and train stations, and anywhere really where you do not get sufficient light. If I'm having this wonderful new technology to augment my reading experience, and it has a battery built in, I want to be able to read in the dark. You are often advised to use book lights with them. but then, why not read a book in bed. At least a book won't shatter when it falls off my chest when I fall asleep.
Two, that eInk screen again. They are horribly slow to refresh, meaning turning a page takes ages. Yes, I know that turning a paper page by hand can last even more, but that's not the same at all! Even if you take your time, and you can't really read while turning a page in a paper book, it does not flicker horribly. In fact, it does not flicker at all. I've seen page turning on an eReader. It blinks! It turns all black -- slowly, then changes content, then turns all white -- again, slowly. It'd drive me mad if I had to see it a few hundred times (yes, I sometimes read a whole book in one sitting). I don't really know if it has to be that way, but somehow I think it may not. Could they not simulate a real page turn, where the page you've just read seems to fold away, slowly revealing the one behind? I'd find it useful, even, as I sometimes speed read the following page while getting "rid" of the previous one. As they're built now, however, eInk eReaders are completely useless to me.
In summary: ability to read in the dark, and almost instantaneous page turning are a must for my perfect eReader. I am literally not getting one if it does not do these two things.
Some eReaders already have this (almost) right, others are hopelessly getting it wrong. Ideally, you'd get a nice, responsive touch screen and have absolutely no controls whatsoever on the reader front (or back for that matter, that's where your fingers will fold, and you don't want them to press keys you can't see).
If yours is an A6 reader, then you likely do not want to take notes on it (or if you do you can live with uncomfortable solutions). Voice notes and simple bookmarks would probably do, maybe with a full screen touch keyboard. For navigation, touch sensitive areas of the screen should suffice, and I also have no problem with well placed (and well designed!)) buttons on the sides and/or top/bottom of the device.
Larger eReaders (A5, A4) could have touch screen keyboards taking the bottom (half) of the screen with various amounts of the rest of the screen showing the text you're reading and/or the note you're taking. Navigation could be done in the same way as described above.
On an A4 eReader I probably wouldn't mind a few (but really just a few) physical buttons on the face of the device, but otherwise, I would have the bezel as small and as indistinguishable from the screen as possible.
It is essential that all controls fall naturally where your fingers are while you're reading away. Too much shuffling makes for a horrible reading experience. Of course, this being the 21st century, I'd expect all keys to be freely user configurable, physical ones, as well as the on-screen ones.
Also, scribbling free form notes all over the screen (underlining, highlighting, too) should be possible on any size eReader. Such notes should be associated with the page they were scribbled on (unless user requests otherwise), and stored together with the eBook you're reading. And when I say that I mean automagically, and to follow the eBook wherever you decide to take it.
Which brings us handily to the...
If you thought these don't attract some stringent requirements, you were sadly mistaken!
Free or paid for, it should be possible for you to take them wherever you want, and I mean truly wherever. You should even be able to print them if you wanted to. You should certainly be able to transfer them to a device of your choice. As stated above, this should also mean that any notes you attached to an eBook you own should follow it to. Examples of devices could be (but should certainly not be limited to): other eBook eReaders regardless of make and model, audio books readers, personal computers. You should most certainly be able to lend the eBook to a friend without having to lend the eReader yourself.
For those worried about piracy, I'd probably allow for a form of protection which will, for example, prevent you lending or reading a book you've already lent to someone, until they return it, and similar restrictions if you transfer it to another device you own. But, you should most definitely be able to do these things, and not worry about compatibility.
Most eBooks are rather small, or at least those with just the words are. Whatever the average or typical size may be, I think that an eReader (of any size, really), should be capable of storing thousands, or at least a thousand. Tied with the requirement that eBooks be fully portable, large size is required so I can take the whole of my library with me as I buy new eBook models. I also don't want to get rid of the eBooks I own, even if I read them, and even if I didn't like them. And, for a voracious reader, going through a book in a day or two is not a problem at all. This means we're talking about one to two hundred books a year. You do the rest of the maths.
It is OK for an eReader not to have huge memory itself, but to rely on a memory card. This will likely mean it can be cheaper, and the choice of appropriate memory size (and the associated cost) is left to the user. It would work very nicely for me, and it can also make it possible to lend the eReader itself, but keep hold of your valuable library. I know eReader manufacturers wouldn't like this last scenario very much, but if the car manufacturers learned to live with it, surely they can, too.
This should ideally be a few days. I do not think week(s) is really necessary. If you really are going on a desert island and want to take your eReader with you, bring a wind-up/solar charger or some spare batteries. the rest of us surely have places to plug in every few days. So, if the only solution for my screen requirements is LCD or similar power hungry technology, just make it efficient enough to be able to run the reader for 36-48 hours (non-stop, of course), and all will be good. Easily replaceable batteries would also be good for those who want to pay for a spare.
Oh, the price!
I do not think an eReader has to be very cheap, provided eBooks are considerably cheaper than the paper ones (they should be, there's essentially no cost for manufacturing and distribution). Still, it has to be cheaper than a similarly sized laptop/phone/PDA. If it's not, why wouldn't I use a more general purpose device instead. In fact, I already am: I read on my Nokia N810, with a view of downsizing (only in size!) to an N900, which is also a phone. For some reading my Acer Aspire One is also acceptable. On all I can do much, much more, too, and all have been (apart from the N900), cheaper or as much as eReaders I looked at.
So, the summary of summaries is now in order...
In short, what I want out of my eReader is the following -- and remember, ALL of the following: A5 or A4 size (or both), touch screen, no controls on the front or back, screen that refreshes instantaneously and can be read in the dark, eBooks that can be freely transferred, removable battery that will last for two or three days, memory large enough or backed up by a memory card slot. Oh, and it's not to break the bank, either!
Know of something with all this goodness? Comments section below is made just for you!
In the end, I did not link to any current eReader (or much else for that matter). Why would I? There's none that are good enough, and you should all already be familiar with all the concepts above. If you're not, do ask, and I'll explain in the comments.