I used it without problems twice. They are also very responsive and pick up the phone or answer email immediately. They will tell you what documents are missing etc and how they were requested by fcvs. For example, my program had a short delay but I was able to clear it up because fcvs relayed which part of the process was missing and i could ask the residency coordinator to send it. Still kind of pricey. I think if you either have a lot of time for them to chase things down (months) and don't follow up, or are willing to be proactive, then you'll be alright.
Also, if you have a few different transcripts (post bacc etc) it's nice not to have to rerequest every time.