OKCupid has a nice interface and the questions it asks are a good way to get to know someone. The people (at least in my experience) seem real. I've used it in the past, been on loads of dates and met my last long-term relationship from there.
Having recently become single, I decided to try it out again. Unfortunately, they have changed the site in such a way that only messages from people who have 'matched' will be seen. Basic dating site maths means this enormously reduces the chances of meeting someone you get on with, and your messages aren't likely to even reach the inbox of the intended recipient. At the same time, if someone has messaged you, you won't see it unless you've seen and swiped right on their profile beforehand. You might have been sent a dozen messages and not know about any of them.
A really nice site, spoiled by a weird attempt to kill off connections between people. It's still possible to eventually match with people by spending hours swiping away like a drone, but remember that there are many times more men than women on here, so the chances that you'll even be shown to a woman as a possible match if you're male are pretty low (assuming it randomises users when showing them on the match screen).
The changes have significantly reduced the popularity of the site, but I suspect they were done as someone's pet project and they're too stubborn to reverse things.
I'm now having more luck elsewhere, hopefully they'll see sense and change it back.