The music is pretty nice, and the "level end animation" looks pretty good.
However the cursor is a little small, and sadly there isn't really a difficulty curve, it's a flat line: The difficulty is the same on level 1, level 5 or level 20.
Edit: The game is definitely not too difficult, rather it's hard to lose. :P But it's definitely good to make it welcoming for really beginners as well, this way