Excellent concept and execution! Like you said, very similar to (but not quite the same as) my own entry. Top notch presentation is let down slightly by inelegant UI buttons and no indication of where you've got to. But those are minor niggles really.
I finished all the levels. Glad you added the negative balls rather than a level fail. Spent a bit longer than I probably should have finishing them all. I kinda had to though, given what I made myself.
Great work for 48 hours!