I was disappointed that all of the levels were simple and pretty much the same thing until the last four "hardcore" levels. Each new level, I was hoping for something more to be done with the gravity flipping mechanic - something creative or different or interesting - but there was nothing. Even the hardcore levels weren't much better since they only introduced one new thing - boxes, which are themselves uninteresting and overused in platformer games.
I liked the art style. The sprites are cute and fresh and very solid. The only problem I had in this department was that the spikes in the Anger side look very similar to the Anger side bushes/plants. Same outline, same color, same saturation, etc. Design wise, the decorative sprites shouldn't look anything like important gameplay sprites like the spikes.