Out of the ten levels 2 and 5 took the most trial and error to get *just* right. The rest of the levels were pretty easy to figure out, although again I sometimes had to retry several times to get it perfect.
Level 6 was kind of funny... I got it on my first try but the ball was rolling so slowly I kept thinking, "Aw, crap... its not going to make it to the ne- Oh, hey!".
It would be interesting to see if there's more than one way to complete some of the levels...