OKC pretends to cater to diversity, but it fails.
The questions they ask are often easy for some users to interpret differently based on their beliefs regarding the subject(i. E. monogamists and swingers may give the same answer to a question about cheating when they really mean two very different things), making match scores inaccurate. To make matters worse, they ask open-ended questions as multiple choice, and ask many that are nearly identical to others. One of my top matches is actually an ex who I now know is one of the least compatible people I've ever met.
They also bias their search results by pairing popular people with other popular people, and keeping many of them out of the results for the unpopular, as if this is high school again. They've actually sent out mass e-mails to the popular members announcing this. The popular members don't need any help meeting each other. Us plain people are who dating sites are supposed to be catering to.
They don't have any filters nor indications of transgender status, other than a few questions thrown in with the personality questionnaire(which only affects your score, and doesn't filter your results like gay/bi/straight and male/female do). I hate not knowing whether or not the member would be attracted to me or want to kill me(or even worse, both) until I actually talk to them; it's a very volatile issue, more-so than homosexuality which they do choose to accommodate. I've been harassed numerous times because some people get angry when a transgender person appears in their search results.
It may be free and easy to use, but I have yet to meet a single person worth meeting in person because of these practices. I'm sure it's a great experience for gender-conforming monogamist prom-queens, but if you're not already at a social advantage, it's difficult to accomplish anything.