Marcus's gravely voice has always bothered me, but it seems like the voice actor has dialed up the angst for the role which reduces this character to an even more absurd level of unbelievable--even in this fiction.
It's funny that you say this, as I specifically remember thinking that the voice actor for Marcus sounded much better than in the past.
I put about an hour into the single player so far. I think it's absolutely fantastic. You can tell they've had almost 3 years to polish this game. Controls are spot-on, the action is frantic and fierce, nicely paced so far. I'm playing on normal and it's extremely easy so far, haven't even come close to dying, it really feels like the easy setting.
Graphics are fantastic, lighting is great. No weird clipping, no post-load texture pop-in, no tearing, nothing weird. After about 20 minutes, I decided to kick in 3D mode, and fucking WOW. Best game I've played in 3D across both the PS3 and 360. The resolution takes a major hit which is pretty noticeable, but I honestly didn't care. It still looks great and the depth is very, very well done (when cranked to the max).
The amount of shit to unlock in this game is fairly astounding. It will keep people going for quite a while.