I don't know if anyone will see the correlation or the comparison but this is how I imagine things.
I look at Super Mario Galaxy is the ultimate creation of a 3D platformer, you do not have to think about controlling Mario and the game play becomes difficult through difficulty of performing tasks in the game rather than controlling the character.
I feel this way about MGS4, I have loved immensely every other MGS game in the past, my favourite game series behind Starcraft but the thing that annoyed me was the difficulty of the controls, I recently played MGS3 and found everything awesome but I was also frustrated by the controls and how complicated it had become.
MGS4 is like the Super Mario Galaxy of Combat games, it is perfection in every way controls wise. I don't know how they did it but right from the start I jumped in and automatically just played, I didn't have to think about the controls and they are so much more defined than MGS3 and before.
Easily the best game play in the series, and I haven't finished it yet so I don't know about the story but I'm digging the BB's, the twists, the tie ups and the variety... it's freakin awesome. I feel like I'm playing and living in the MGS world and I feel sorry for Snake. Insane game. I don't want it to end, haven't felt like this about a game since Zelda Ocarina of Time.