What I can give as advice is:
1. If you have the intentions of completing the almost identical maps in multiplayer over and over again (like for instance L4D/2) you will like the multiplayer, because it wont be anything different. It will be fun the few first times, but after that when you continue seeing the same things over and over you'll probably stop playing it and then you are left with...
2. A story. Which probobly won't be good. Sure, it will be epic and funny like the first, but really how many times can you go pass the same story with 1 ending for 60 bux?
It's your call, I say go pirate on the game and play it, then if you like it buy it.
Mod Edit: Piracy