I too did a brief comparison with my 650 to the nook when I last visited B&N. I'm satisfied with my 650 and don't see any need to upgrade to the nook Touch at this point. Admittedly, I haven't had a lot of time to play with the nook, but I do think the Sony's interface is better than the nook's. (Although the new nook is much better than the classic!)
A few things--I find Sony's dictionary implementation much superior to the nook's. With Sony, you double click on a word and get a brief definition at the bottom of the screen--then you can expand that to full screen if you want. You can then scroll back and forth through the dictionary and look up words by entering the word. With the new nook, you can look up a word, but after getting the definition on the screen, there's no way to scroll through the dictionary and I couldn't find a way to look up a word by simply entering it on the screen.
From what I've read here, the new nooks don't support multi-layered Tables of Contents. I have several books that have these, so that would also be a problem for me.
I also don't like the fact that B&N has tied up so much of the new nook's internal memory for use with B&N product--from what I've read, only 250k of the internal memory is available for side loaded books--what's up with that?!
And finally, why not support landscape viewing? I don't understand B&N's decision not to implement this at all. Sony's landscape mode has a little to be desired, but at least it's there.
All in all though--I was impressed with the new nook--and if I choosing between it and a Sony 650 at $229, it'd probably go with the nook--I could buy quite a few books with the $90 price savings!
dordale