Very good!
I enjoyed this very much! I just recently found out what Sudoku is, probably just last Thursday, I got a Sudoku on a piece of paper from my Math teacher as an extra assignment for bonus marks, which meant that I didn't have to do it.. and now I see this, weird. Good job on the game though, very solidly done, sucks that there's no sound, but it's good that I get to listen to my music while I play it. Um, the graphics are WONDERFUL, they're very slick and smooth. And you have a great style for doing it. Very good animation too for the menues and number boxes, and everything else that was animated. I hope you make more, maybe with some cool sound effects. Or secrets that you can unlock, or extras, whatever.. just make more! This was excellent!
Ps. I think this is probably my longest review ever! ->haha =P