I have one good friend on here who I could never have met irl (geography). In the past I've had a couple of online friends, one of whom died (we had a close friendship), it was a very different strange sort of grief with nothing tangible to link to, no friends in common, I still think of her and miss her. Yes people can be fake, but I had many reasons to believe she was the real deal.

I have no one on fb I haven't met irl (a rule we had for our son and I stuck with it), and I have to say on the whole I prefer face to face interaction - it feels more natural somehow and nothing beats being in the room with people and having a good laugh together. I do keep in touch with my rl friends in-between meet ups with email and fb though and I like expressing my thoughts in writing and reading others thoughts.

I have valued my online only friends but I have to be honest it's not on the same level as rl friends.