According to the Project Completion Rating system, you can receive low % scores even if you did the project quickly and the client liked the work. According to how it works, if the client fails to release milestone quickly enough, you receive a fail under that rating. That is bullcrap.
Another issue is if you CLEARLY stated the client must make a milestone before work starts, yet they refuse to do it. So you end up aborting the project and again your Project Completion % score goes down, even though you did absolutely nothing wrong. I think whole Project Completion rating system is horrible and freelancer did not think clearly before they implemented that.
In my opinion, It can really make someone look like they aren't reliable to do the work even if their work is perfect. Utter nonsense.