I'm on Facebook, and I definitely use the security settings. I don't have any personal info on there besides my name. And I use the setting that blocks farmville and all that stuff from my wall. Anyone who utilizes the security features should not have problems such as identity theft, stalking, etc... I just always remember that whatever I write, I'm writing for the whole world to see.
I love seeing folk's photos, and hearing what they are up to. If someone writes too much offensive or boring stuff, I just hide them so I don't have to read it. I also hide farmville, and all the other games. I have played some of the games myself, and it's probably worth it to be on there for that reason alone.