An existing Sony Reader owners comments...
Firstly, let me say that I can't see ebook devices ever taking the place of traditional books - I love my own little personal library of books, neatly arranged and with gorgeous cover artwork. However, ebook readers are fantastic in the same way that mp3 players are; massive mobile collections that are incredibly convenient.. especially when you don't have enough physical space to store everything (my shelves are all full!)
I've owned my Reader for a good few months now - imported from the US earlier in the year.
It's a revelation compared to any existing display technology; when I took it out of the box and bubble wrap it was already on (must have caught the power switch fumbling with the packaging) and the screen was on - I thought it was one of those transparent plastic covers they put on display equipment in stores. There is a slight pause when 'turning' the pages (better on the newer models), but it's very slight it's just one of those you get used to when reading a different medium, like reading a really thick paperback with your non-dominant hand for example, or a large sheet newspaper - the experience is *different*, but not annoying as such.
You can tilt the device to any viewing angle you like - even almost totally side on and the display is perfect. Once the screen has been set it does not need refreshing, means no eye strain and extremely low power - I get at least 2-3 weeks use out of the Sony, with reading a few hours every other night.
To those wanting a back light - it's not possible with e-ink as the screens are opaque.. but just as a normal book you can buy a clip on light if you want. Other than the obvious places (the bath!) you can read content on the Reader anywhere you can read a paperback; from dim rooms to bright sunshine outside etc...
The comparison with the Kindle is obvious and yep, it doesn't have a keypad or wireless, but I prefer to think of it this way - would you want wireless and a keypad on your ipod? Most people are quite satisfied to download stuff on their computers and then sync to the device.
However, it may not be the device for everyone. If you're interested in one of these or others, then the best thing to do is get over to www.mobileread.com
BTW, The device works fine on Vista 64 - it's just the installer doesn't run to completion: check here for how to fix it; http://www.mobileread.com/forums/showthread.php?t=26849
Finally, you don't have to buy books from Waterstones; most other ebook formats can be converted via the excellent Calibre application and there are thousands upon thousands of books and novels in the public domain. I haven't bought *any* ebooks yet and I've got hundreds to read through!