I've been working as a freelancer since 2011, and the first website I've used was VWorker (that was bought by Freelancer). VWorker was like 1000 times better. They would take care of their users by holding the money until the job was done, and if the freelancer delivered, and the employer was happy, the money was released.
But with Freelancer, that's another story. You don't have any kind of security that you will get paid for your job. I did a small project for 100$. Freelacer withdraw from my balance 25$, because I've accepted the project. I did the job, deliver it, but the employer did not paid me. In fact he just ignored me. I've tried to talk with someone from Freelancer, because I don't think it was normal for me to pay the acceptance fee, for a project I was not paid for. But nothing!
So bottom line is that I've PAID 254 do work for free!
Also, they have a habbit of withdrawing money from your paypal balance, and if you don't have money in your paypal balance, they will charge your credit card that is linked to your paypal accout, so you might want to cancel your Preapproved payments to Freelancer from your paypal account.
Later Edit: here is the username of the employer that scamed me: FoxScully