I've used doublelist for a few days now. No successful hookups yet, and here are my two key criticisms:
no relay capabilities yet. When you receive a reply after posting, you have to communicate via your explicit email address. Not the best approach for those replies that don't result in a successful meet-up (which in my experience is 50%-75% of replies). However the creators emphasize that they are working on masking email addresses, which CL does very successfully.
very very small audience so far. I think that will change as more ex-CL readers learn of the site and migrate over.
These points aside, I think that Doublelist could emerge as a viable replacement site. In time.