I really enjoyed this game, and played all 30 levels.
There were a few cases where the shapes didn't reset back to their original positions after a failed attempt, but other than that the levels progressed at an unfrustrating pace, and I never felt the game was unfair.
Correct me if I'm wrong, I did find the stars at the bottom don't really made sense. They seemed to be tied to how many shapes you get correct, but since you have to get all the shapes correct to pass the level, you automatically get all the stars. Maybe if stars were more timer based on how quickly you can solve the puzzle, or how many attempts it takes, then you could have levels where you didn't do so well and only got 1 or 2 stars.
Really good game though, I am quite impressed with the amount of thought that went into the puzzles.