+ Wonderfully intricate puzzle design that always knows just how much to ask from you, so the puzzle is always 'how to execute' rather than 'what to do'.
+ Inventive use of boss battles in a game where there is essentially no other 'combat'.
+ Runs smooth as butter, and the effect of diving between orb worlds never stops being impressive.

- What little can be picked up of the story is a bit too abstract for my tastes.
- Later puzzles can feel like a lot of carrying puzzle pieces around, even after you've worked out the solution.