Over one year, I have been able to test three different e-readers :
A "Nook Classic" (no touch, but a small touchable LCD screen),
A Cybook Odyssey (Touch)
So, I'll make a short and highly subjective three-way comparison, using the Nook Touch, which I have used for the longest duration, as the reference.
The Nook Classic's LCD screen was quite usefull : the second "accessory" LCD screen allows an easy and intuitive navigation, color covers display. It also serves as the keyboard. However, it was restricted to an "off screen" zone, and gave for dictionary and annotations access a mix of directional arrows or virtual keyboard. It also hampered the autonomy, by being quite energy inefficient.
On the opposite, the completely "Touch" technologies, used by the Sony and the Odyssey allow a direct and easy access to those through selection directly on the reading zone. There exist though a difference between the two : The IR solution, used by the Sony, has a far better precision and finesse than the 'overlay' used by the Odyssey. When simply reading though, it has no real impact.
The Cybook Odyssey wins largely this one. The screen (while a little bit more darker) is really crisp. The big font and sizes selection is also a great bonus.
The Sony is from this point of view more trustworthy. The button, even if not really well placed either (especially with the "light" cover), is frank and works well. However, the ereader also has some bugs, related to fonts (italics and bolds), features a lesser number of font sizes.
All in all, the best compromise may have been on my Nook, with its four physical buttons (one each way on each side) and no fonts problems. But it's screen is dead so ...
One can also find disturbing the "no search" feature on the Odyssey
Regarding covers reading, there seem to be some problems with the Sony, among others for ebooks added through the SD card. It may be corrected by re-exprting through Calibre, which Sony plugin manages covers and collections.
The Cybook Odyssey is perhaps the best one for navigation, having an integral "Folders" navigation mode. Too bad that some functionalities don't work outside of one specific folder, for example the "recently read" list.
PDF files reading.
The best for PDFs is by far the Sony. Despite the quite disconcerting flashes, one can easily select and change the focus in the pages. The 2 columns or 3 columns mode also work wonders. The Odyssey and Nook are on the other side too slow and not flexible enough.
Once again, he Sony is the one that works best. The virtual keyboard (not as good as the Nook's, but better than the Odyssey's) allows an easy annotation writing. The "manuscript/drawn" notes is more of an accessory,but could help sometimes in the future. the Sony also agives an "all notes" list for each book, and allows filtering/searching through them. The PC/Mac application, although of an abysmal quality, allows an import of the annotations.
Other bonus for the Sony : the external notes taking application, this time again with the drawing options. My daughter loves them ;)
I think I have a quite good vocabulary in French, so don't really use this dictionary. From that point of view, the Odyssey's dictionary is almost useless for me, while I missed dearly its English dictionary (but Beta tests are starting for it). Likewise, I don't in the least miss a French dict. on the Sony or the Nook. But clearly, the "Touch" functionality is best for accessing the dictionary. Clear winner, once again (for me) the Sony.
Here, it's a clear win for the Odyssey : access of the Virgin store works flawlessly., whereas buying from the Nook was impossible for me (due to B&N enforced georestrictions)and while the Sony reader's link t the Google Store could work, it seems not to be up (yet ?).
Everything works all-right, for the Nook and the Sony. On the other side, for the Odyssey, USB connection seems difficult and frequently cuts out. For me, who mostly buy through non-affiliated sites, this clearly was a real bother.
A more minor bother on the Sony : of the 3-4 wall-chargers that I could use without any problems on the Nook, only one works on the Sony. So if you want to buy a charger for your Sony, check it out before !
Only ereader with a correct internet access : The Sony. The "experimental" browser from the Nook was worthless, and for the Odyssey, browsing is where the "touch" technique used is the baddest : too imprecise to select any link with precision, it mandates a high zoom level.
Here again : Point Sony .
That's a geeky thing, for sure.
Not much (if any) on the Odyssey. On the Nook, one could root and install android applications, but the additional screen restricted installation to compatible ones. The notes and checklists aplication was really the only one that justified for me the Root.
On the other side, on the Sony, it's a whole world that presents itself. I haven't taken time to really search, but it seems I could install for example the Kindle app (Berk) or OPDS compatible reading apps.
I have not yet configured the dropbox application yet, but will do it soon ! In the meantime, the calculator can get handy.
Last but not least, ther's 20 euros between the Odyssey and he Sony. From my point of view, and since I annotate, and want to be able to use the internet, that I have no interest in the Virgin store, the choice is easy.
So, the Sony it is. with one small remark : if the Nook's screen hadn't failed me, I'd most probably kept it, and wouldn't have had to spend 150€ right before Christmas.
Edit: 22/06/2012 : The "updated" Odyssey seems to be MUCH better, no USB bug anymore, enhanced fabrication, better power button. I've got really good feedbacks on that version. So if you plan and buy an Odyssey, make sur you get one with the "push" power button, not the "sliding" one.