Being a gamer since I was 10 years old, and constantly gaming since then, i'm not sure if the quality of games or the thing that appealed to me is disappearing, or if i'm just getting old.
MAG is a pretty solid game, it doesn't do anything that will 'WOW' you. I can see the appeal of why people would buy this, and if you've got a bunch of friends to play with, and intend to play with them constantly, by all means, teamwork is valuable and it will be an enjoyable experience. However, if you have no friends with PS3'S and want to go into this alone, not many people have microphones, and it is the same verbal abuse that you encountered in Halo and other games today.
Graphically it's okay, I personally didn't like the shiney graphics as they seemed odd looking to me, but it's certainly not an ugly game considering the amount of players in the same room.
Gameplay is solid, it is a decent shooting game as that is what it was intended to be, it is no hybrid.
It never sucked me in, as I only played for a week or two, I fear the next time I want to give it more of my life, and another chance, there will not be thousands of people playing it Online.
If you're considering this game, and you have friends that are going to play it too, I would recommend it.
If you're going in alone, i'd suggest renting the game or borrowing it from a friend, as personally it didn't grab me as much as I thought it would have.