Depends on how you deal with your account. I've only added people I really know, and want to keep track of: anyone who I can't be bothered with I accept as a friend and then after a couple of months I remove them.
My account is locked down as tight as possible (excluding bugs of course), so much so, that somebody I sail with said they weren't allowed to add me as a friend even knowing when my email address (could have been a bug)
I have an account because it allows me:
To see what members of my family in Ireland are up to (namely niece & nephew)
To see what friends in Germany are up to.
An easy way to see photos from friends without clogging my Inbox.
What I don't do:
Bad mouth my boss (he's a mate of mine anyway so he knows when I'm pissed off)
Add photos of me pissed, etc.
All it takes is using a bit of common sense, unfortunately that appears to be lacking in today's society. At least you see almost daily reports of somebody seeing the consequences of being an idiot, so maybe things are improving.