I kept dying on Level 3 and couldn't bring myself to keep going. I think I would have appreciated a slightly more forgiving life system - it could even be tied in with the glowing orbs you pick up (e.g. every 10 orbs gives you a heart)
Funny enough, Level 3 was also the level I enjoyed the most, because of the challenge. I just didn't like starting over from the beginning every time. Skills issue, I know!
Great game, overall - I really like the visuals, excellent audio, and I think making the level circular adds an element I haven't seen before in similar games. Well done :D