It's a mixed bag.
On one hand, it's a pretty nice idea, and the implementation isn't bad; on the other hand, there's a bunch of things that bug me about it.
The game is buggy in various ways: the shot estimator doesn't always show the right trajectory, some (?) upgrades show a cost of "UNDENED" when you go too high on them, and the game breaks in various ways if you finish and then play again.
Planet upgrades are a mixed bag; on one hand, having planets for bouncing is good, but on the other, they get in the way and block access to stars once you got more than a few upgrades. (If this is by design, I'm not sure it's good design.)
And finally, if you play for a while, it gets far too laggy. All in all - it's OK, but it could be a lot better still.