There have been a lot of concerns in the last year or two about what Facebook does with our details. The Timeline feature caused more worry as it looked as if the network would make public even those details and messages that users did not want to share. The network denies this, and it's certainly true that it's not alone in its practices. Just now there is a lot of discussion about how social networking sites - not just Facebook - collect our data and use them for targeted advertising.

Apart from privacy issues, I know people who left Facebook because they were finding the chat on there was just too banal, or got tired of getting messages they didn't want - invitations from Farmville and that kind of thing.

Generally, if you are careful about what information you put on the network and who you make friends with, it's probably harmless, but you can still see it as a waste of time. This debate may give you some more ideas.