The controls are fine, the game is a great logic puzzle. Enjoyed it very much.
I was expecting something simpler, like 2048. The margins are hard to control at times.
I'm not sure how happy I am with the margin controls, either. This is really designed to be a mobile game--and rows and columns are swiped. I tossed a variety of other options around, and clicking the margins seemed to be smoother than, say, click+drag. I've been getting some good feedback, though, and may be able to figure out something a bit more intuitive.
Horrible controls, confused as to even play.
I revised the built-in tutorial that launches the first time the game is loaded. That should clear up any confusion about the controls.