I'm still trying to wrap my head around the fact they are releasing the 13 inch pro with a high res screen and no discrete graphic chip. For normal computing it's going to be fine, but I wonder how it will handle anything 3D intensive or even heavy Photoshop work. At this point, I think it may be worth waiting for the reviews to hit. I could be wrong, but I have a feeling this may end up being a mistake on Apple's part.
I will say that the Pro is giving you a much beefier processor, out of the box, then the Air gets. Some of that horsepower will be used to drive the additional pixels, but it's not like you won't see a nice performance boost with it. External dual screen support is a big plus too.