Yes, it's complimentary for all business and first class travelers. However, be aware that there is nobody standing there to make sure that people getting into that line are actually coming off of first or business class cabins. So in my experience when there is a back log with long lines then all lines including that one will be long with a long wait time.

From my own experience as well as those of family and friends arriving around the 3:30 pm timing, sometimes it's nearly empty and you can breeze through in 15 minutes and other times it's jammed and the wait is 1 hour+ even if you use the fast track lane. There's no way to predict what the wait will be.