Great game!
I love the sounds effects. It gives the game an ominous feeling to it, like i'm playing with bricks that weight tons!
The physics engine is amazing. I love/hate when i get a big tower going, and the whole thing crumbles with a deafening BOOM.
If you plan on making another, i would suggest making bricks that look like steel contruction equipment. and/or add smoke and dust effects for when it falls apart.