Runs fairly well on my laptop (2.0 GHz AMD Turion, ~900 MB of RAM), bit there seems to be a lot of swapping going on, so the game gets choppy at times.
As for opinions; the controls seem fluid, and the collision detection works well. Pushing the blocks seems a bit odd, as they just get nudged around by the grid, isn't there a way to make them actually just slide smoothly, as entities of sorts? Solid AABB's, with the touch code just shifting 'em around, I dunno, I'm not too familiar with Game Maker.
Visually, the game looks pretty nice! The character reminds me of Cyanide and Happiness, which is awesome. The tile graphics could be a little better, but I figure you're doing the game all on your own? But visually, very nice. I can't say much about the character having the cyan outline; perhaps a solid color would work better, rather than outlining? Same could go with the rest of the visuals, having the end result looking much, much smoother.
Great concept, too.