I like my nook because you aren't tied to amazon's kindle books. Also, the touchpad at the bottom allows you to swipe to turn the page which I like.
The page turning is a little slower than the kindle, but it's not a dealbreaker.
My friend has a kindle 2 and i have the original nook. After the 1.5 firmware upgrade, the Nook turns pages faster than the kindle. Both are really good for reading since they use the same screen, but here are the key difference:
Kindle 2:
pros: lighter (but not by much)
pros: Battery life (the kindle's batter life is vastly longer than the nook). I usually get a week to a week and half of reading before having to charge ... this is with 1-2 hours of reading a night and keeping it in standby with airplane mode on.
cons: stuck to the amazon store. No support for epub (but my friend told me that they have the ability to send the epub to amazon and for 50 cents it'll convert it for them)
Nook:
pros : open standard, supports epub .. side load epubs with calibre.
pros : 1 hour reading on entire barnes and noble libraby when in store.
pros : Free stuff at the barnes and noble stores when you show your nook...this month is a free tall smoothie.
con : battery life
con : the lcd screen at the bottom is unresponsive and hard to use.
Hope that helps.