1) You can level your character the way you want by spending points in the skills, weapons and attachments that you actually care about.
2) There are contracts which act like mini-games in multi-player. You buy a contract with your experience or 'money', and then should you fufill the contract, you get a larger return... otherwise, you lose your purchase price.
3) The game has a co-op zombie shooter game on disc in addition to the multi-player and single player campaign.
I didn't buy my copy so it's worth every penny to me.
