For anyone deciding between the two, I'd definitely suggest checking out the demos (there is a demo for Skate 1, right?)
Skate 2 is without a doubt the smoother of the two. And the viewpoint is a bit easier to deal with. Between that and the many other improvements (ability to walk, more tricks, shinier look, etc) I'm guessing most folks will prefer Skate 2. I've only played the demo at this point (many times), but it's looking like I'll prefer 2 overall myself.
However, as a long time skateboarder [been at is since the Animal Chin days of the mid 80s and, for what its worth, I won my first real life game of SKATE just yesterday with a tre flip ... not bad for an old man ... chuckle] ... anyway, there's just something about the feel of the first game that I really like. For those of you that are bigtime skate video addicts, especially if you dig the closeup perspective often used in, say, Zoo York videos, I wouldn't pass up the first game. It has a slight fish-eye perpective that makes you feel like you're controlling a skate video ... moreso than Skate 2. I especially love how the perspective changes when you are trucking down a hill. You feel the speed. [I'm guessing this is still a part of Skate 2 ... no hills to bomb in the demo so I wouldn't know]. The perspective can be a pain at times especially when dealing with trees and pedestrians at high speeds. But you eventually get used to it and it just looks so amazing.
Also, the tricks pop differently in the first game. I like both to be sure, but there's something extra rough and raw about the tricks in the first game that appeals to me. It took me a couple of times through the demo to start liking the way tricks were animated in the new game. Though now I've come to see how the style in Skate 2 is keeping up with the big/smooth/bangers style made evident in places like theberrics.com.
Anyway ... I could blab on this all day. Both games are unique and great. I'll grab Skate 2 soon and I'll cherish them both.