Decent idea, so fix it!
The biggest problem for me was the control of the blocks. As a few others have indicated, it was slow, and requiring a click ON the bar to release it was a real pain (because of the slow movement). You should change that to a click anywhere, at least.
Unfortunately, I have to rate the game as it is, not as it could be -- and as far as I'm concerned, it's unplayable. Work on the UI.