Love it, but I see 1 problem: when I see something on Facebook like: "I just bought Product X and unlocked a 10% discount for YOU", I presume it's spam. Copywriting is going to be very, very important to this.
See the recent LivingSocial Amazon promo on Facebook for an incredibly successful example of this model.
Ultimately this is up to the user, but our goal is to expose our observations about what works to our customers to make it easier.