^MGS 4 was nothing like that TGS trailer, unfortunately. KojiPro was experimenting with getting an optional FPS mode into the gameplay, but they didn't get it right. In the game's actual FPS mode, Snake couldn't run, couldn't jump, and couldn't do any sort of cool finishing CQC moves.
MGS 4 was the biggest release in the franchise, but also the biggest let-down in the technical capabilities that it was promising at TGS and E3. I fully understand when Kojima he said that he'd personally rate the game a 1/10, because there was so much he wanted to do, but couldn't. I hope that he'll be able to achieve what he wants, with a new console!