Nice idea, good graphics and the music fitted.
Good level of difficulty and new elements were added as the game progressed. I sometimes felt the new mechanics were sometimes neglected after being introduced, after bringing them into the game could more have been done with them?
Music and the "look" of the game start to feel a bit samey as the game goes on, even though the gameplay itself isn't repetitive (there are a variety of challenges, some more puzzle and some more skill) it actually starts to feel as if it's the same thing again and again. I think you should consider changing the sound and look as you progress through the game. A greater sense of urgency in the music in the fast-paced more skill-based levels? Change the blocks from futuristic and clean to ancient and ruined-looking with more apocalyptic music? Anything that adds a bit of variety really, even if it only seems superficial.