For the love of god do not waste your money on Revelations 2, even if you loved Revelations 1. It's horrible and gross, and I'm not saying that as someone who isn't super into the action-oriented side of RE, but just as a game itself it's really, really badly made. Multiple short "chapters" (ala the way that Telltale Games release their games, except much more incoherent and short), multiplayer without having multiplayer (as in, the AI constantly screws you over). It's just bad. I even loved RE5 and had a blast with it, with or without a friend; this game literally bends you over for not having a human next to you.
All the others are awesome, and I even have a special place for 6 despite it being my least favorite (I really consider Rev2 to not exist), but Rev2 is pretty much everything bad that Capcom has done in one single game. Even though there's characters in it that got me super excited before they showed any gameplay or anything, they do nothing with them. It's one of the only games I actually wanted to refund, but missed the time frame.
On the bright side, if you end up getting it, you can at least play with others if you can find anyone willing to play it (I think); the Steam version doesn't even let you use actual multiplayer...which...boggles the mind in a game so forced to multiplayer.