I liked it, but I do have some suggestions.
1. The music while you are playing is ok. However the music durring the level summary (where you see your score) kind of sucks. And the drastic difference between that music and the music of the levels probably makes it seem to suck more than it actually does.
2. I would prefer to be able to rotate the gems that I am controlling of my own accord,
3. It would be nice if the playing field was a bit larger in comparison to the gem size.
4. As this seems to be set up like a puzzle game (the movement isn't random the gems seem to have pre-set paths and speeds). It might be nice to be able to just go through the levels and then re-select them like many puzzle games.
5. I don't know how long the game is (I haven't had a chance to play more than a few levels and I have to leave), but it is always nice to be able to just come back to the game and pick up where you left off.