No matter how you spin it, IRL is completely different from the Internets, though I have a lot of friends on the Internets. IMO it's hard to convey feelings over the Internets, because it's sort of the same thing of trying to convey feelings over a giant wall, just transferring data back and forth.
I don't have any particular opinion on it, because a lot of my friends do it, IRL and on the Internet, and they seem happy to me. I wouldn't do it, but I don't really care if someone I know does it, just if I don't care if someone speed dates (does that still exist), is bisexual, has some weird fetish that they'd never tell me, etc.
I have plans to meet up with some people I meet on the Internet if I ever swing by their way, but of course I know them well enough to want to meet them and chill out or something. I honestly think meeting them in person a few times without committing anything is the best way to go. One of my friends in my singing organization is getting married to her bff, and I'm totally going to Scotland in a few years to attend!
Actually I interact over the Internet a -great deal- with my best friend, but at the same time we have like 5 classes together and go to the bookstore every week, and she says the way I act on the Internet is slightly different from the way I act online. (I am more crazy and prone to be stupid IRL)