I also got to play with a Kindle 3 over the weekend. Interface and overall looks I love the nook way better than the Kindle. Perhaps it has to do with the I-like-what-I-know syndrome but I really love my nook. However, screen clarity (obviously due to the pearl screens) and page turns are clearly Amazon's victory without counting battery. Page turns don't bug me as much on the nook but after playing w/ the Kindle I cried a little inside.
However, with all that I would still choose a nook over the kindle 100% of the time IF I could trust the battery a little more. I'm hoping for one more update or a revised nook but the battery life really gets to me specially coming from prs505. I could turn wake that thing up a month later after not using it and still have battery to read while the nook, even in sleep and in airplane mode needs to be charged every week whether i'm using it or not :/