I don't want to talk too much about my personal life here, but I used that particular service for a few years. I had some funny dates, some ok dates, got one long-term girlfriend, and then I met my wife on there. She wrote me, we went out for dinner, and we've been married 4 years now.
It's just like anything else on the internet - go slow at first, watch out for "too good to be true" profiles, and try to write something funny. It helps you stand out.