Do You Have Any Experience Of Using An Online Dating Site? Which Site? Was It A Good Or Bad Experience?

I’m a member of OKCupid which is a free online dating site which works via matching personalities through the amount of questions you answer. I’ve met numerous people via this site and have had a year long relationship with one of them.
With the exception of my ex boyfriend, all but one person I’ve met via this site (about 6 people) has failed to contact me after the first meeting. In some cases it was obvious that there was never going to be a second ‘date’, yet in the other cases these were guys that I got on really well with (no awkward gaps in conversation and a generally nice day/evening).
My profile is up to date and has relatively recent photos on there (so they know what I look like before meeting)… I should also point out that there’s never any physical contact – just a handshake or friendly hug so it’s not as if they have sex with me and then disappear. I also pay my way – getting in the first coffees and taking turns.
Anyone have experience of online dating? Am I encountering more time wasters as this is a free site? Is the ‘disappearing’ thing common? What’s your story?
Thanks in advance :)