Overall good
First I will say this is a a good game and that i liked it. However i do have some suggestions for improvement (some of which other reviewers have already mentioned).
Colour the dark blues although usable probably where not the best choice for both the cube AND the background.
Controls most of the time thay where ok but when it came to rotating the cube the buttons proved to be very cumbersome, if possible try for a click and drag the background to rotate the cube.
As a whole this is a very good puzzle game.