Just a couple tips:
Best characters to use to get around on foot are either Mecha Zangief or Zombie Frank. They can plow through crowds with their dash moves, and their Y attacks can clear the way easily as well.
during Case 5, when you investigate the small room in the compound, one of the clues says, "fine art is so 1995". In the original game, there was a Christmas wreath you had to remove to solve the clue. In this mode, in order to solve the clue, you have to SHOOT the painting above the sofa. I thought my game was glitched until I did that.
For the boss fights against Tom and the female mercenary...use Dante for Tom and Sissel for the girl if you have him unlocked. Sissel can pretty much destroy her since she won't be able to touch you if you constantly melee her.
Also, the final battle of the game.....just use Sissel. He is untouchable when using his attacks. Just run up to the boss and melee him to death. He'll never be able to hit you.
other than that, if you've played the campaign before, its the same as you remember. Super quick now that you don't have to worry about side quests and maniacs.