It's pretty well designed, for something so simple it was pretty fun. I feel that the ball should bounce, similar to a rubber ball.

LOL! I used the same tutorial, "How to make a game in unity" - by Brackeys. I know what tutorial you used ;D. Anyways. Its fun, but need more collectibles.

This game is quite perfect, and definitely not bad for a first game. It's quite challenging.
I only didn't really like level 6. This is because of the power ups.
The blue one that seems to make you go faster sometimes suddenly wears off, for some reason. And without it, it's impossible to jump on the very last moving platform.
The green one is not very intuitive, because it doesn't always give you enough force to make it all the way up, and there is only little you can actually do about it, which can be frustrating. It would be slightly less frustrating if there wasn't a hole directly before the green piece.
Also I want to note that I think I encountered a bug which makes the game forget the checkpoint, so when dying you suddenly go back to the start. Happened to me twice.

How did you make the UI, im struggleing a bit in my unity games??
Else A good game! Maybe the game would look better if you tried to go for a more cartoony textures and look!

The physics look weird at first, but it gets interesting later.
I guess the challenge is in the physics, otherwise the obstacles and platforms and jumps would be too easy.

If you replace the ball with a bouncy car tire - like that ones you see on Donkey Kong Country (SNES), the physics would make more sense ^^