At its best, the game is one of the most original puzzle games in a while. At its worst, it has some puzzles that genuinely make me want to stop playing and never come back.
I think the biggest sin this game has is its save point locations. Some puzzles will kill you again and again, and you'll have to backtrack again and again, with less and less inclination each time.
The worst puzzles are the ones where you know what you need to do, but the controls and level design just make the process tedious and not enjoyable.