Just woke up and found this out myself. Has this ever happened before? Hell they even went on after 9/11 for Smackdown. Not sure if they have some kind of streak going or not. Either way I see people already speculating it's some kind of angle, which actually would be kind of interesting. I doubt it is though.
Definitely clunky by today's standards. Never had a problem with the controls back in the day, although, by the time Snake Eater hit they were definitely outdated. But seriously, once you get them down (which is no wizardry) it becomes second nature to you, like most games. They aren't overly complicated or anything. I had a blast myself playing through Sons of Liberty "along" Dan and Drew. Snappy and fast paced is how I'd describe my personal replay-sessions.
My personal advice as someone who has all those games under his belt: Wait for Metal Gear Scanlon 3 to finish before you tackle GZ. I can't imagine it being a great experience going into the Phantom Pain's prologue (which GZ is, let's not fool ourselves here) without knowing any of these characters. In fact, everyone appearing in that little game except Snake/Big Boss is either straight out of Peace Walker (which I don't mind, since I loved that game) or a new character altogether. It might sound like a hassle to catch up on so much stuff, but if you enjoyed Dan and Drew's journey up to this point, you really should continue going along in order. And thinking about it, these games aren't THAT long after all.