I played through the first 200 puzzles of this game. The game gives a good amount of content (500 total puzzles)  and has a nice clean design that gives the player a frustration free interaction. I didn't find the puzzles too difficult, averaging less than 2 minutes a clear and few puzzles pushing 10 minute mark (milage will vary based on player skill). I think it provides a nice distraction when played in spurts.