It took me several times trying and setting the game down to come back to it before I was finally able to beat it. Very fun game. The controls initially felt very floaty/weird but once I got them down, it felt really good to move around (it was so much easier for me when I switched to a gamepad instead of the keyboard). The art is gorgeous, and so is the music, though the song did get a little repetitive since it took me so long to win :P
My favorite part was the heartbeat sound effect. The change in panning was subtle, but listening closely to that was the thing that ultimately let me win in the end after several times of not even getting close on the last level.
Really fun, and I'm glad I came back to beat it; I can rest easy now knowing I didn't let my poor sister down :)