This is a very exciting device. Nice screen, a font folder to allow you to add fonts by putting them in the folder, MobiPocket support, pop-up menus, lots of font size choices, and (WOW!) a nice dictionary look-up! I'm drooling a bit.
There will certainly be tradeoffs. iLiad, of course, has the nice big screen. Sony Reader has more buttons, and is a very solid device. And there are still some unknowns with Bookeen (maybe they were answered elsewhere?)... other formats supported, battery life, boot up time, standby mode, clock, dock, "hackability", memory card support, mp3s, etc
We're getting so close to the point where an "Average Joe" might be interested. If only the price could drop just a bit more. Once these kinds of devices are <$100 look out!