I think that the ball should stretch a bit as it falls down. It makes it look more "bouncy," which (I think) is the effect you want to achieve. The bounce back up is great though.
The momentum is pretty poor, it needs to gain speed on the way down faster, and lose speed on the way up more before it begins to fall again.
Yeah, someone else said the same thing, I'll try lower the frame rate when it goes up a tad.
@ I sort of stretches a bit when it is about to hit the ground. I think that if I add one more frame a bit before it hits the ground it'll look better. I'm on it :).
@ Kittygurl521 Thank you!