This game is insanely hard! It's also insanely infuriating. So many different kinds of games you have to win and master, almost all of them hard to do and relying on insane levels of both skill and luck.
Truly only a very few can manage it all. I almost gave up for a time there but I only had one more left to win and I pushed myself and somehow managed it (after many many many times of failure)
This is truly a game only for the hardcore gamers.
Somewhat interesting with the score boosts after you win all 40, to add something of a replayability into the game, at least for those interested in climbing the high score tables.
Warning. If you don't have the patience, do not play this game. You have been warned!
I did feel the ads were a bit excessive though. Fair enough -- you're trying to get some ad money and deserve to be compensated as well -- but it interrupts the flow quite a lot with the frequency of them.