Madridman and all:

I used Aerocity last month from the Hostal La Plata. It's on the Gran Via about 5 minutes from Puerta del Sol. I also had an early flight and did not want to worry about getting a taxi.

Hostal La Plata reserved the shuttle for me, they were on time and it was 20 Euros for both myself and my friend. It was great and I would highly recommend the service and I would used it again.