Pretty standard "Throw the ____" game
I love these kinds of games. Maybe if you another one have some other different types of upgrades. I feel they really make the game when it comes to this genre.
Aside from that I have no complaints, but I can't give too high a score because it didn't exactly bring anything new to the genre.
Great game all in all though.
On a side note: That is one HUGE city...maybe you should have incorporated changing backgrounds as you move further so there aren't cities spanning hundreds of kilometers lol