I had fun playing it and getting to 96% the second time :D The shop is a very nice touch. With more songs I'd have played enough to buy a lot of content :)
There is one thing though that I did not understand : I clicked when the squares were perfectly in the center and did not get "Perfect" but I got it by sometimes clicking when the squares just arrived in the area (and it felt out of rythm - too soon).
Can't wait for more content !