I am still using CL and so far so good. I have still gotten good tenants on my last few rentals and am getting some good choices right now on a unit I am advertising. I owe it the LPA pre-screening prospect card. Of course you get all kinds of losers on CL, but like the newspaper ads or anything else, you have to separate the good ones from the bad ones. The prospect card helps me do that. See John's article on it at http://www.thelpa.com/lpa/what/prospectcard.html
It only takes 1 good one. I'll sift through a hundred losers to find one winner.
But of course there are other sites besides CL like Trulia and Postlets that are great for rentals.