Friendly and attentive staff -buses seem a bit old.
Automation for valet check in and pick up is excellent.
Although the App shows where the pick up buses are it can take some time!
It just works... it's mostly seamless. I park, get on a bus, and get dropped at the departure terminal. A couple of weeks later when I return, I (hopefully) pull the card out of my wallet, the spotted van is there, and I'm at my car in a couple of minutes. Your drivers, the face of the company, are always pleasant and helpful.
Parking isn't cheap, but it is what it is. I live about mid way between Newark and Dulles and flip a coin on flights. I need to start factoring in cost of parking as Newark is higher on parking but cheaper on flights.
Close to the airport. Reasonable rates. Rarely have to wait more than a few minutes for a bus. Enough parking spaces so you don’t have to circle around and around to find one. Opportunity to earn and easily redeem points is an added benefit.