I love my Nook. I chose it due to the fact that I can download library books for free. Which is a huge plus and saves me a lot of money.
Nat has a kindle as well as do several of my friends. However I have not spent so much time side by side with anyone until Nat to realize more of the differences.
The battery on the kindle lasts a lot longer, maybe 3 weeks compared to my one week with the Nook. The kindle is lighter and smaller but not by all that much.
Nat has been downloading books from Amazon the whole time we have been in Mexico. Yesterday I tried to purchase some books from B&N, but they can only download if you are in the US or Canada. That is a bummer.