I've tried online dating but the basic problem is people have that buffer zone where they don't have to reject a person. That's the main downfall. When talking to someone on the street (figure of speech) you have to look them in the eye and possibly see the hurt of rejection and all that. When you're just ignoring someone on a website you can make believe there's not a person on the other end.
The other problem i've seen with online dating is that people generally tend to over-sell. When you meet a member of the opposite sex irl, they don't come off as "take me to a beach, then sky-diving, skiing, water-skiing, now, now, now" However a lot of peoples online profiles try to make it look like they are the most exciting person ever.
Then there's the logic gap between men and women. As a guy, I go "hmmm I like computers, I should look for someone within the realm of that interest. Online dating!" While women go "I have no interest in computers and am barely computer literate... I should try online dating!". You literally find a lot of outdoorsy people doing the online dating thing. So by that logic, the best way to find a gamer girl or at least a gaming-tolerant girl is to go outside where people are playing sports. (?)
So yeah, not getting a reply from people is pretty common.