The big deal is that it's the ONLY big-named thing that Sony had exclusively. GTA4 is now multi-platform and they didn't have too much in the way of first- or second-party stuff (Killzone was even absent), so it was really the big thing for the PS3. That and the gyroscopic sensor in the controller.
MGS was amazing, MGS2 was decent, and MGS3 was incredible once you got past the Cobras. So I'm lookin' forward to it 'cause the last one ended so damned well, but it'll be about 5 years before I play it due to the cost of the PS3
I was there on that fateful day, were you?