My impression and experience with ProZ.com is positive. I get the majority of my clients from there. I use the services, like the Blue Board and the webinars, I watch the International Translation Day each year. I've spoken to someone from ProZ.com regarding my rates and she was very helpful. I'd say the yearly fee is totally worth it. I think ProZ.com is definitely on the side of freelancers, I think it's a great platform and I'm so glad I found it.