This game is beautiful, well crafted, and clever.
The animations are squishy and the sound is pleasant making the occasionally-very-hard puzzles go down smoother. The non-linear world map also helps with this. Oftentimes it'll be easier to solve a puzzle once you've figured out some of the common techniques on different levels.
The challenge in this game is like Progressive Matrices or a spatial intelligence test, only more dynamic (and adorned with misleadingly cute, often fratricidal animals).
Mac port is nice too!