http://forums.gametrailers.com/showthread.php?t=405557
The reviewer deducted points for the story being too complex, and for there being too much shooting.
A poster on Neogaf who has read the review also said there were points deducted for the game repeating the same mistakes made in MGS2.
The magazine is a casual only magazine BTW.
This is awesome for MGS2 fans like me, I was worried the story might be dumbed down like MGS3's.