So apparently everyone on here is complaining about the cost and relatively close relationship to Mercs that the new DLC poses to Resident Evil 5. Is this DLC worth the money? Absolutely, take it from one who has bought it.
This new DLC is something that has never been tried on a Res game, and in my opinion brought ResEvil to the next-gen games. It does seem like Mercs alot at first, but isn't that exactly what all other games' online are? Was Capcom obligated to make something crappy that was new, or something good that was just an enhancement? People have yet to realize the actual value of this DLC.
Now on to the actual DLC itself. You get basically 4 NEW game modes for right around 5 bucks. Honestly, you're not going to miss those 5 bucks when you buy it. It adds more depth and achievements to the games, and lets you show off those handy Wesker unlocks (heh heh). Not only that, but the entire online Slayers is basically a giant "Zombie Holocaust" (NOTE: Please don't get offended by this analogy) where two teams take on each other in a shoot out against zombies...and you can kill each other not to mention. Now obviously the game has a few drawbacks, such as a seemingly OHKO with a shotgun to regular zombies. But the game implementation is great.
CapCom released something that Epic failed to...Lobbys. (at least in gears 2). The DLC takes advantage of showing you several lobbys with various players in them. You pick your game type you want to play, the game shows you which lobbys are open and voila! you're playing. It's hardcore fun for the hardcore gamer.
All in all, I highly recommend this DLC. Don't let cost turn you off on this fun multiplayer zombie raping action.