Some observations on the Odyssey, in random order:
1) You can hide the header (it displays the book title) and/or the status bar (it displays the reading progress). So, the "screen consumption" can be adjusted by the user.
2) You can tap to turn page. Personally I do not use this feature that much, because of the side buttons (much better placed than those on the SONY PRS-T1).
3) The screen of the Odyssey is a Pearl e-ink screen, with a capacitive layer. The grid is visible only at very low angle (from the screen plane) and with very bright lightning. It is not noticeable during while normally reading, when your sight direction is roughly perpendicular to the screen plane. Overall, the screen is slightly darker than SONY PRS-T1 and Kindle 3, but it does not hinder the reading experience at all.
4) Fonts: on the Odyssey you can load your own fonts, so you can even copy PMN Caecilia (the Kindle one), if you like it. Moreover, the Odyssey can override the EPUB CSS, justify/sillabate the text, and it also handles ligatures nicely.
5) You can copy your own dictionaries on the Odyssey (altough it is amenable of some improvements), that you can create by your own (with my Penelope script).
Overall, I enjoy the Odyssey more than the T1 or the K3 for its superior reading experience, as you can customize it more than the other two. Unfortunately, Bookeen made a couple of very bad design/manufacture choices: the microUSB and power switch are plain mistakes, the USB driver is buggy, and it lacks a search function and a "back-in-history" button.