not me personally, but i have several friends that used them to have tons of casual hookups. That's not something i've ever been into but i guess if you wanted that it works. i also know 2 people who have met their spouses on them so you can go that route also and i'd say it works.
I also know a person that i believe has undiagnosed mental illness and he claims they don't work at all. my point is i think it's up to you whether they work or not but i have no clue if any of these people are paying for any of these apps.