The game is really fun and addicting. I'm at Puzzle mode 75, while the earlier puzzles can be solved in creative ways, the later ones have obvious "right answer." (But you can still manage to save a couple pieces.)
Some stages are badly designed, even if you get the concept nailed, one part placed one pixel off can cause your system to miserably fail. (And moving it by a single pixel solves the system.)
I haven't tried Action mode yet, but I assume there'll be about 50 levels in action mode. (If Puzzle mode goes up to 100)
I wish there'll be harder levels later on, as current chapter is still easy.