I beat it last night. The ending theme is so fucking terrible. It's "Save This World" terrible.
Some of the effects used in the game are pretty crazy. Visually the game was impressive as hell, but I still think the first game had the best campaign. The second and third games try to get into telling a bigger story and it just falls flat, the same way the second and third Pirates of the Caribbean movies did. The character interaction in the first game just felt so much better. They started shoving in more characters in the second and third games and it ends up suffering from Spiderman 3 syndrome... too many characters you don't give a shit about.
So when are we gonna get on some coop, man? Roll through some horde mode.