^ And after that, there's another whole stage. Don't forget that.
Truth be told, once you master it, you could beat it on the easiest skill level in 4 hours. But you will not master it that quickly. The game is next to impossible on the normal setting, and there's two unlockable difficulty levels after that, which I can't begin to imagine ever beating... and it's my favorite game of this past generation.
I mean that, sincerely. The game is absolute gaming perfection, from blissful gameplay to a spectacular presentation, I can't easily name a game that I can say is as well-rounded.
For 6 bucks now, you shouldn't have to ask other people how it is; I'm telling you to buy this game. You absolutely will not be disappointed if you have the patience to see it to the end (2 or 3 times).