Good concept and plays decently.
One or two issues though:
1. Every damn thing shaking during the opening of each level as the wall descends. Nasty on the eyes.
2. No pause button.
3. For some reason, a couple of times when I played, I launched the ball and within seconds every building exploded all at once. I see no in-game explanation for it.
4. Twice while playing, the wall seemed to land on top of buildings, making them impossible to destroy.
EDIT: Yes, the yellow hexagonal wall landed in such a way that it was on top of one of the buildings. It was the later level with lots of concrete walls and many buildings.