Looks great and plays well, although it does quickly lose its charm.
I didn't quite get how the upgrading mechanic works. Sometimes I was able to make it work and other times I didn't and I had no idea what I was doing wrong. At first I was also overwhelmed by all the different types of bricks I had. I think having each type should be slowly introduced throughout your first session as you keep playing until you can play the entire level with every option.
Can I call it a tower defense game? Because it's totally a tower defense game.