Really neat idea, with the awesome twist of "joining two genres together" ! That's a really clever take on the theme !
Overally the game is enjoyable ! Graphics are cute, the game is simple at first but becomes harder, and I love the general concept ! It reminds me of Tuper Tario Tros, a (very) old Flash game that mixed Super Mario 1 with Tetris elements to create the platforms ^^.
Just one drawback : the controls are a bit unintuitive. Having to rotate the tetris pieces with the same hand that controls the princess (and not the pieces) was disturbing. Maybe "IJKL" keys for the tetris pieces would have been a better choice ? Or maybe the numpad (but rip TKL users...) ? That's hard to figure...