Terrible physics!
The start of the game was quite good - it's simple, fun and easy to get into. However, as the levels got gradually more complicated, the poor physics engine kicks in. Balls don't bounce off walls properly, it's impossible to shoot through a small gap, and (something that got VERY annoying on level 20) shooting too close to a floor/wall caused the ball to warp towards it and collide.
I did complete level 20 in the end, but it took a ridiculous number of shots.
Another slightly annoying feature to this game is when you accidentally shoot a ball into a vertical, wrong coloured cup. The cup ejects the ball straight up and almost always catches it again a few times before usually releasing it. Why can't it just fire the ball out of the cup in one attempt, every time? Re-catching it seems completely pointless to me.
If you fix the dodgy physics (even if you intended not to make the ball bounce much, still let us shoot much closer to floors and walls), then I would rate this game more like 9/10. But for now, it's really nothing special.