I can say that I am very pleased with my Sony PRS600. Here is a quick run down of what I like.
Screen is clear, and I find eInk to be a lot easier on my eyes than a backlit screen. Gesture for page turn is minimal, or you can use the buttons. You can 'turn down the page' for future reference, make notes, and highlight. The included software is very nice,and you can use calibre with it too (which I like better, personally). You can format your own text files in Atlantis (free to try) and save them as an ebook which can then be loaded onto the reader. The unit is nicely designed, and is very comfortable in the hand. There are several font sizes that you can switch between. Ebooks I have bought from other sites work just fine on it, although you DO want to watch your format to be sure it's acceptable. It's also great on downloads from free sites such as our own mobileread forum and Project Gutenberg. I'm sorry I haven't encountered any PDF's yet; can't speak on that issue. I am very pleased with my reader, and I'm glad I made the investment. Please ask if there is anything more specific you'd like to know.
