I only really used it once. It was last year in Savannah, GA. Both good and bad. It was something along the lines of a Hampton, although I forget the actual hotel brand.
When I arrived at the airport I didn't know I had to call it special, and that it didn't make regular runs unless called. I figured that out and called, and then waited 40 minutes for it. And apparently she picked up others and dropped them off at different hotels before I got to mine, so the hotel was sharing the service from a contract, not an in-house deal.
I used them again to get to some shopping and restaurants that were too close for an Uber or taxi, yet too far to walk. Service was pretty good that time.
Generally though, I am someone who absolutely HATES sharing transportation with strangers except for Rental Car shuttles where I really have no choice..at least it's usually a short ride. I will NEVER use Supershuttle or UberPool, or any other service that requires me sitting with a stranger other than the driver, or making stops. That's for Kettles and "budget" travelers.