Anecdotal counterpoint: I know of at least 2 instances of people who have met on eHarmony, via paid accounts, and have proceeded to end up in very solid relationships.
I know no such success stories with OKCupid.
I know no such success stories with OKCupid.
With online dating in general, I think what you get out of it really comes down to what your attitude going in is. I saw sites like eHarmony and OKCupid as primarily ways to be introduced to more people. If I struck up a conversation with anyone, I'd ask to meet them fairly quickly, and would approach those dates with a pretty laid-back, no-obligation, "let's meet this person and see how we get along" attitude. Going in relaxed like that really takes a lot of the pressure off and makes it easier to just get to know someone.