I was attracted to an e-book reader as a way of carrying lots of books around with me, once e-ink came along and looked so easy on the eye. I spend a lot of time on computers at work and home, so reading on a backlit screen (PC, mobile phone, ipad) really isn't attractive to me (despite having colour) as I want to protect my eyes (and in my late 40s now, this gets more important!).
Here in the UK, the choice is mainly Kindle 3 or the Sony 350 and 650. At least, these are the most commonly available. Being able to try them out hands on was very important to me.
At first I had thought the Kindle would be better - bigger screen, whizzy marketing portraying it as the best and most versatile, blah blah. But I was underwhelmed! Navigating via a cursor key around the screen seemed a retrograde step after being used to a mobile phone I use every day with a touch screen. Plus, it seemed quite big and awkward for something I wanted to hold in my hand for long periods.
I tried the Sonys. The touch screen was a delight to use, so intuitive and was a big draw for me straight away, despite the extra cost (the 350 here is slightly more costly than the lowest price Kindle). And while the screen technology is the same as the Kindle's, Sony's font is easier on the eye, to me (it is slightly different - another reason to try these things out yourself before buying I think).
I had thought I wanted a 6" screen but the 350's 5" screen was fine in use, and the unit was that much smaller, lighter and easier to handle. Plus the 650 is quite a lot more expensive (and less commonly available).
The size, shape and lightness, and the touch sensitive screen won the day for me. Wireless/3G I don't need. I can load up the Sony with more books than I will ever read (well almost) and I'm not someone who has ever thought "I wish I could download book X and read it now". After a week I already have enough books to last me a year, without coming close to filling it up. And all free. I've been finding gems in the public domain (I'm reading Mark Twain for the first time). And e-ink is easy on the eye.
I still buy paper books (I LIKE paper books) - whether I'll ever like the idea of paying close to full price for an electronic file to read the latest book on my reader...I don't know. Then again, I still buy CDs, not mp3s.