One big difference is the retina display which is just Apple's fancy way of saying that the screen has a very high resolution. The resolution is so high that is hard for the average person to see all the digital pixels on the screen. If you do a lot of reading you might want to think about getting the new iPad.

Before making up your mind it might be a good idea to try out both if can in a store. If you have an iPhone 4 you'll know how sharp and clear everything is with its retina display. You will get this benefit from the new iPad.

I personally dislike reading for a long time on the iPad 2 due to the lower resolution. You may not have that problem.