I love this thread. I actually am on FB, but also agree w/most everything said here. I limit myself pretty strictly most of the time -- checking in maybe once a month or so, but then at times I do get sucked in and start checking every few days for a week or two. Then it gets old and I drop it again. I post a couple times a year, but refuse to do the mundane status updates w/random opinions, links, minor daily events or musings. I've considered dropping it altogether, but can't bring myself to take the plunge yet, because i have so many far-flung friends that I do enjoy keeping up with. Problem is of course the ones I care about the most are not the ones who post most often.
I think my biggest issue with it is that it often *doesn't* make me feel better about myself -- just sucks me into comparing my life w/countless other people's lives, and comparing my lack of one-liner wit/humor with others. So, generally i don't miss it when i disappear for months on end, but then eventually something brings me back to it. AND -- recently I was fortunate enough to be connected to an old friend on FB who would not otherwise have known how to contact me to let me know of the tragic death of a mutual friend. That eventually led to a reunion of about a dozen or so old friends in the place we all met originally, most of whom had not been in contact with each other over the years. SO -- i see a few advantages now and then, and guess that's what keeps me on. I foresee a day though when i'll eventually drop it altogether.