This game (well, demo) is fucking brilliant!!
I love the way that they have incorportated the thumbstick. When even doing a simple ollie it seems as if you really have to set it up right and actually concentrate on actually "doing" the ollie instead of just hitting a button and your stats determining how big you can ollie. Not to mention the numerous trick various that come up because of stance and feet position.
I also like how you need to finish tricks and can't get too greedy. In Tony Hawk if you ever find yourself in trouble all you needed to ever do was hit grind and lord knows there will be something to grind on. Hell, once you get so far in the Hawk series you end up doing 20+ trick combos just to get high enough scores to move on... I can't see this happening with Skate.
Besides the camera angle, which seems like a very poor choice if this is the only one, I can certainly see some challenges getting very frustrating. With so many different tricks relying on what point the thumbstick hits the angle and how far you circle it, I think it's safe to assume there will be some tricks that you are asked to do that you will end up not getting the motion exactly right.
I don't think I've been this geeked over a game coming out since I was a kid...I can't seem to get enough of the demo already.
edit-- Now if we could just get a next gen Dave Mirra!