It's my favorite franchise, and the only real reason I bought a PS3, other than GT5.
Seriously buy it. If you haven't played the previous games, play them or at least brush up on the story first. There's a free download from the PS Store called Metal Gear Solid Database which has the details on the on-going plot, characters, and side stories of the entire series. If you go into this game not knowing the story, you won't have nearly as much fun, and most plot twists and details will go straight over your head.
I didn't read anything about the game before I bought it, because I wanted to be impressed. I knew it was going to be good, but I was completely blown away. They outdid themselves on this game. The first ten minutes you're like "yeah this is pretty damn good" but after you get past the second act or so you're just like "
If you have a PS3, buy it. If you don't, buy a PS3 and the game. And if you have time, play the first three games. It's worth it.
Discuss.