I've played for about 10 hours now, and I have to say the game is great so far. I was somewhat disappointed by the demo, and also the first part of the full game (ie the demo + a bit more).
But as I played, I got used to the controls and features of MGS3. The camera doesn't bother me much at all anymore, all the gears (like radars and such) aren't just there, I actually USE them frequently to my advantage (apart from the AP sensor). I thought the lack of a radar would make the game a chore, but as it turns out I've become much better at sneaking around than I ever was in an MGS game before! The game really encourages you to sneak around.
Lying camoflagued on the ground and swiftly standing up doing some CQC is really satisfying.

But I have to say it's really hard to avoid the guards long enough if you're discovered. There are usually no defined places to hide (like in MGS2), and it doesn't work by just running to the next area or lying down being camoflagued either. Usually I just die or kill every soldier. Is there anything I'm missing? :/
I really appreciate them cutting down on the "codec" talk, it's VERY reduced compared to MGS2 (or better managed, I don't know), and there's a LOT of gameplay without interruptions at times.
Maybe this will sound strange, but it almost feels like there aren't ENOUGH cutscenes in the game, especially for all the different bosses...I remember when you got the background on all of them, but now you barely get to know anything. Doesn't bother me much though, but still...