I played the demo without the CPP. Controls just like Peacewalker, meaning, perfectly fine. I thought the visuals were nice. Not RE:R nice, but then again, RE:R looks better than PS2 games. There is some framerate issues with the cutscenes. Not while playing the game, which makes me think this demo wasn't optimized with the new character models in cutscenes. One thing MGS2, 3 and 4 do is use higher quality models in cutscenes than during gameplay sections, which makes perfect sense.
I saw nothing wrong with the demo though. Seems like an old build to a good superior version of MGS3. I am actually torn if I will even use the CPP with this game. I had zero problems using the face buttons for the camera. It felt like as if I never put Peacewalker down.
Day 1 still.