I've put about 70 hours in so far. I took a break and got back into it. I'd say in terms of depth, graphics, just the overall game is a masterpeice. The story isn't as linear as precious metal gears but it isn't supposed to be. My fav MGS is probably MGS3 as I loved the survival aspect of it and he setting. I like the buddy system in PP, it adds a feel of team work I've not gotten offline before. When you kill a soldier you really fee like you've killed them, the way the bullied goes through the skull is pretty scary in PP. when D Dog or Quiet get shot you really genuinely get ****ed off and concerned! That says a lot about the immersion of a game.
I recently purchased Falliut 4, yes different game styles but MGS feels more real, Fallout feels more scripted, stiff in comparison where as PP takes me away from thinking it's a game..weird to explain.