If FaceBook was up front about its privacy policy, i'd be fine with them sharing information...but the fact is, they pulled a bait-and-switch by first promising privacy, then significantly altering the terms of the agreement under which i'd signed up to allow for wholesale sharing of my information. It's this underhandedness that i, and many others, abhor.
They're also blatantly dishonest. I've been getting notices that say "your friend X recommends you befriend Y", but i've confirmed that these messages are generated by a FaceBook algorithm, NOT submitted by the person whom they say.
If it weren't the only way to know what my family members are up to, i'd swear off FaceBook in a heartbeat...come to think of it, i might anyway...