Now I love facebook as much as the next person but twice now I have been unaware of parties that I have been invited to because the person invited me via facebook. And not like posted to my wall or something directly but via the event reminder thing that you get no notification for. Sure it sits in the upper right corner of my facebook page but if I don't check over there (and I don't) then I never see it. In both cases the person (different people) acted like I was in the wrong for not being aware of said upcoming party.
Listen people, it's not my problem that you're too lazy to send out real invitations or even bother logging into evite to make an email one. Just because you slap it on an event calender doesn't mean I'm ever going to see it or even care about your flipping Lia Sophia party that you couldn't even be bothered to mention to me personally. Find someone else to drop a hundred bucks on a necklace for you.