I have a Sony Reader Pocket edition and love it. Very convenient and easy to read. There is also a lot of free content out there via libraries and some retailers. If I were buying one today I'd buy the 6" kindle ($139) and not the DX. With the zoom capabilities I don't have any issues reading on a smaller screen.
Also, I know some may like the 3G options or WiFi but my current Reader has neither and I don't mind it at all. Of course, I might see the purpose behind the convenience if I was reading newspapers on it.