I've been watching the whole eInk thing for a while and finally gave in at the start of the year, going for the entry-level Sony PRS-300. It doesn't have any form of wireless, or any snazzy note-taking features, 'cos all I really want to do is pre-load it with books and read them.
Specifically, I don't want to load it with papers or highly-mathematical books. Novels and maybe some light compsci, yes. The reason for this was the eInk technology - page refreshes are slow (a noticable fraction of a second), and eInk (and indeed most electronic book readers) is really bad for flicking around and browsing, which comes up a lot with the heavier reading where you can't just start at the beginning and read through.
My experience so far has justified this, which is kind of ironic as it's actually a lot better for light novel reading than for the kind of technical text a gadget early-adopter might read. As a novel-reader, this kind of technology is excellent, as it's smaller and lighter than a chunky paperback, let alone a hardback, and it can store a decent number of books. On a commute, you needn't be stuck if you've finished one book and want another.
So, on to the specifics of this device. It's a standard Sony product. So, the hardware feels pretty nice. The firmware is mediocre, and the PC-installed software is dire. Starting with the PC software, it's taken a leaf out of iTunes's book, but copied it very badly. iTunes on Windows imports an Apple look-and-feel... the Sony software on a Mac has a nasty, inferior widget set that e.g. gives really ugly context menus. The software is laggy when it's not downright locking up, and it seems to manage to screw up syncs as often as it can, and have random arbitrary limitations. Yay.
On to the firmware. I've not been using 'proper' ebook formats, since I have little interest in buying DRM rubbish. The formats which look most convenient to me were therefore PDF, RTF and plain text. Most PDF documents render too small to be readable on the 800x600 display in normal portrait mode, but the firmware does fortunately have a landscape mode, viewing a single page in two chunks. If your document has a big margin, it'll happily display this, but fortunately Apple's Preview application allows easy cropping of PDFs, so that it'll take up the entire reader screen. Why is this not built in?
PDF display is not all fun-and-games, though. It can be really very laggy to switch pages. Why not pre-render and cache the adjoining pages, to remove the render lag? Moreover, it's sometimes rather difficult to tell when an operation has started. The eInk is no good at quick updates, but why not have an LED for 'I'm thinking'? There's a charging LED built in already - why not use that? Some buttons require you to hold them down for alternate operations. So, a tap for next page, a press for skip 10 pages. Of course, there's no feedback for when you've reached the 'press' period of time, and it will only start grinding away once you've let the button go, so you've got to guess the minimum hold time that'll get you forward 10 pages as quickly as possible. Argh! So simple features implemented so badly!
Having said that, PDF's been pretty reliable for the docs I've got in that format, although if I had a document in a different format I wouldn't convert it to PDF. I've seen one or two rendering bugs (cheers, Sony), but they've not been killers. So, what's a good format if you have the choice? The software doesn't allow you to specify an author name on a plain text document, and when I briefly looked at it it had some particularly braindead handling of paragraphs, so I quickly dumped it. The RTF support is certainly good enough for novels - 'A Deepness in the Sky' (one of my favourite-est novels, evar) worked very nicely for the 1000+ pages it had. However, I tried converting an RTF with lots of pictures in, and it gave up rendering the text part (but kept the pictures!) after a hundred pages or so. Useless. Oh, and HTML support? I switched to RTF because the HTML support was pretty dire.
Finally, the hardware. It feels very pleasant. The eInk really is very pleasant to read - I've been reading various documents off it for a couple of months now in every morning and evening commute, and it's much more pleasant than the alternatives. The build quality is good. It claims 'up to 7500 page turns', and I can support this claim. Specifically, there's absolutely no chance of it exceeding 7500 turns on one battery charge. I'd be surprised at 2k, and given one paperback can come in at over 1000, I'd strongly recommend taking a charger if you want to take this thing on a holiday. It's surprisingly irritating to be unable to read a book you're carrying because its battery is flat!
All-in-all, it's definitely immature technology. It's too expensive, slow, the particular implementation has Sony's renowned software, and the ebook market is still screwed-up. However, it makes a great novel-reader, and it really does look like the thin end of a very long wedge which will eventually make my lovely bookshelves look as useful as a vinyl collection. I'd give it 15 years.