I think both companies fumbled with these devices. They could have been serious challengers to the Kindle, but there are weaknesses in both. Well of course that depends on your needs.
The new nook is worlds better than the old one, but I had a lot of ghosting problems inside the store when I was using it. It was unreadable at some points. On the nook board, its thought to be due to the sun. I didn't see the ghosting at night. As Lat said above, the memory is limited for non-B&N books. This is a real killer for me as B&N is not a store I have bought from on my ipod.
The navigation on the nook is great. Its easy to get around and find what you need. Highlighting is a bit iffy. Its not very accurate and I am not sure if its firmware or hardware. No where near as smooth as the Sony. The dictionary is easy to call up while reading. It not obvious like on the Sony or Kindle, but it works well once you get use to it.
I haven't gotten my hands on a Kobo Touch, but I am disappointed in it. I really liked the Kobo I had, but returned it. I found I wanted a dictionary for all my books, yet the Kobo still doesn't off this. This is their third model and they still don't have this basic function? The company released a press release yesterday saying they were going to implement this, but I feel it should already be there by now.
I will probably end up getting a Kindle here soon. I always like the screen, but disliked the keyboard. It was between the Kindle and Sony. I liked Sony a lot, but wanted to wait to see the new Nook. Now I can't find Sony anymore.