Okcupid is like Netflix for pussy.
Especially in New York City. I don't consider myself a PUA or anything like that, but living there and using that website to score dates is like fishing with dynamite.
Interesting thing is, everyone's on there. If you're single, that's probably where you are. Even girls who go out, be social, meet guys in the conventional way - almost always have an OKcupid profile up and running.
It has completely desensitized me to dating, which is both problematic and a blessing. You end up dating multiple girls at once, having sex with all of them, struggling to keep each person's name and life organized in your mind. You have to constantly be considering where they are, especially if you are out in the same neighborhood - it's a dangerous game, to be certain. Mutual friends are dangerous. Facebook will help you find any problems like that.
Setting up and going out on dates constantly is actually incredible practice. I think that okcupid and other dating sites have significantly improved my chances of getting somewhere with women that I meet in person, over the years. It's an improvement of social skills and interactions with complete strangers. You want to attain that cold, fearless confidence that both genders fear and respect.
Anyway, there's no reason not to. It only improves your chances of finding someone really decent that you respect and want to be with (if you're seeking a monogamous relationship). I personally am teetering on the edge between polyamory and monogamy, so I don't know where this will take me.