e-reader recommendations

A friend has asked for advice on e-readers, and I'll admit that I'm fairly clueless--my impressions are based on the original Rocket e-book reader from seven or eight years ago.

I saw a Kindle at Balticon this past weekend, which looked fairly easy to use, and the wireless convenience was cool as the owner bought jpsorrow's book while we were sitting together at the bar.

There's also the Sony e-book reader, or the iPod inspired COOL-ER. And then there's the newly announced mini e-book reader from BE Book which isn't available yet but early review is promising.

Anyone have any experience with ebook readers or recommendations to share? Easy to use, lightweight and ability to handle multiple file formats are all good things. Wireless downloads versus having to download to a computer and then transfer to the reader sounds nice, but is it something that people really use? Anything I can tell them is a must have or must avoid?

Thanks in advance.