This DLC is hardly worth the points for a short, copy and paste, lackluster experience.
The campaign starts off with the L4D2 survivors in front of a raised bridge talking to 1 of the 3 L4D1 survivors, they mention that the bridge generator was overrun with infected and have wounded with them. so the L4D2 must go round through the town to reach the other side so they can lower the generator and leave. Its that simple.
Other then three new maps to play on, very little has been added to the campaign. The campaign features it's own uncommon common infected the fallen survivor (like the Parish's SWAT infected) who either attacks or flees the scene if it spots the survivors and upon death drops a couple of items. Two new weapons are introduced, a golf club which is not different to any other melee and the M60 Heavy Machine gun which shreds anything that is in the user's firing line.
Another new feature is caches that appear through out the level at random, fixed points. Theses have a large (if not infinite) supply of a single item, these can be either grenade items or top-up items (pills and adrenaline) however it is rare for these to be in a area to be of any use. Other then the fallen survivor there is no other new enemies unless you count a skin swap for the witch and a pair of zombie skins.
Overall the campaign is lacklustre, there isn't anything new for players to experience the finale is just a scavenge like dead centre's but with some firing support from the 3 original survivors (the 4th is dead) which makes it even easier to fill up the generator as you will have 6 people covering you.
Nothing is added to the previous five campaigns which seem like a missed opportunity especially with the weapons and caches. Though campaign supports the other game modes (Versus, Scavenge and survival) its hardly worth paying the 560 Microsoft points and not feel slightly ripped off.
An addition to this is an extra game mode called Mutation. Mutation is a different game mode each week changed on the Thursday which it is either single player or multiplayer.
This off the bat feels like it should have been a free patch like Survival was for the previous game as it isn't restricted to the passing campaign. A blog has also been added to the main menu (but this is just a free update) where there is a weekly vote and the latest news about valve and its community.
The DLC hasn't fixed the Survivor AI which boarders on brain dead, seeming to have a 45 degree cone of sight and hearing, with many instances of player losing his life because none of the AIs noticed him hanging off the end of a smoker's tongue.
PC fans have little to complain about as this is free for them but 360 fans should really avoid this DLC as it feels too much like a recycle job with so many things that should have been free in it.