Got a PS3? - Get this
This is everything you could ever want from a Metal Gear game ... and then some. Start to finish, it grabs you by the balls and refuses to let go until the credits roll (and even after that it takes you in for some more!). It became pretty evident during the development that this was the last Solid Snake game and as a result, there was a lot for them to squeeze in and a lot of loose ends for them to tie up, but they were all tied up beautifully even if some characters' endings were more ambiguous than others. If you've ever played a Metal Gear game, you MUST get this for Act 4 alone. All in all - best game ever? Yeah.
Oh and another thing - best final boss fight ever!