I'm playing it. Online servers were turned on this morning if I'm not mistaken.
I'm not a huge fan of MGS but I wanted to at least run through this one. I plan to sell my copy in a couple weeks and write it off as a rental. The bundles at Walmart were a great deal last night (80gig, $100 walmart giftcard, ds3 controller, MGS game for $499).
As for the game...it's interesting, but again, there's problems that make me not love it. Combat is generally awful like most of the previous games (close combat can be dreadful even with sensativity on high). Cutscenes can be too long and boring (Drebit's first cutscene could have been a minute instead seemingly 10 minutes). But, most of those complaints are subjective and everyone has a different opinion. It's very similar to the others, at least to non-hardcore fans of Metal Gear. The introdution of the MkII made it look like Jar Jar the way it was dancing around like a kids toy.
I'm going to keep playing it. I've mentioned negatives, but there's plenty of good points. Graphics are beautiful. Audio is great. Soldier conversations as you are sneaking around is super. It's not going to be on top of my favorite games list, but it's good enough I'll keep playing.