Dunno if anyone else was considering buying this, but I wouldn't bother. It's crap. It is short as anything (maybe 4-5 hours IF you do ALL the side missions and kills just about every zombie you can find), they reuse entire maps from the main game, and it ruins the already lacking story they had in the game to begin with.
Also, no new weapons, no unique item drops. Generally just incredibly disappointing.
That sucks. How did they mess up the story/what map did they re-use?
I can't explain exactly how the story is screwed up without revealing most of the plot and I'd rather not destroy the tiny amount of enjoyment anyone else who buys it might get out of it, but basically the entire thing is like a parody of itself. They just toss in shit for the sake of tossing it in (giant pumpkin headed monster???) and the reused maps add to it.
You go to places that are the exact same maps as in the original just with some new barricades thrown in here and there and the enemies changed to zombies. Even the loot chests are still in the same places, and you can still travel back to the old version by quick travelling to areas from the original game (hell, you can talk to/visit people you killed for that matter).
It was just kind of blah. Seems more like it was meant to be some sort of halloween joke or something, but it's not worth $10.
The FREE DLC that came with mass effect was longer than this...