I don't use it either so he's not the only one; I have an account but a blank profile.
From a marketing perspective I think Facebook is awesome but I don't see any reason to give them personal information and/or develop a history with the site.
Do you really want to create a time line of where you've been, what you like, who you are friends with and in a relationship with, share photos, personal interests, how you're feeling over an ever growing period of time and so on? I don't.
On a side note, I think it's ironic that people give Facebook all this information (who then give it to advertisers) and then bitch about their privacy. You see it every day on "news" sites like NEWS.com.au and SMH.com.au. Every second day they do a beat up about a privacy breach yet all thees people are handing it over for free.
Anyway.. that's my little tirade on Facebook.