I don't quite understand how you could know the gameplay is balanced and fun by just looking at the pics. I don't know how three powerups could possibly be balanced, but then again, I haven't tried a game on it.
Interlocking has been used but sometimes not in the right places for example. The walls on the (what i think is) middle structure stick up and definetly aren't smooth. I'de concentrate on these sort of things before aesthetics but apart from that it's good. 4/5 lost the 1 because i'm getting sick of MLG maps.