Nice demo, keep working on it!
I usually don't review demo games, as they are "unfinished and are not representative of the final product", but occasionally I will offer my opinion and advice if I think it is necessary. This game shows a lot of potential to be the next hit on Newgrounds, front-page-worthy even, if it is properly executed. The game concept is unlike anything I have played in recent memory and it is entertaining.
To improve upon what you have already established, I would suggest you add some music and sounds to your game so that it does not become boring (as well as a button to change or turn off the tracks if they become annoying). The menus were well done, but plain - not that it's bad, but I feel they could stand to look a bit better. Having an option to bind a key to a specific color or command would be a nice feature, but not necessary. As you level up in the game, the backgrounds should also change to reflect that increase in difficulty or change of pace. On that note, adding difficulty levels would be good (could mean that the ball travels faster, the platforms may revert to their original forms more quickly, etc.) as well as a save feature to continue the game.
Yes, this demo shows a great deal of potential to become a truly spectacular game. I say that you should keep working and improving on it to really make it stand out.
[2/5]
/ADV