Been trying out the Beta and congratulations on quite a stunning piece of work, cant recall seeing quite such a well put together product. I only have two observations so far.
First one being a lack of anti aliasing, I suspect you are maybe using a deferred renderer or something so maybe its not too easy to add but really would further improve the look.
Second are the tune levels, couple of things here, first I am soo tone deaf as to really struggle with these levels but the major problem is I have a friend who is totally deaf and though he loves your game his enjoyment of the later levels came to a halt as it is next to impossible to solve these levels if you cant hear, could maybe a light or some other indication as to the order be added sometime.
Again congrats on a lovely piece of work.