Everyone's expectations are different, great service implies exceeding expectations by a significant amount. Tell us how your expectations were exceeded.
The return trip is pretty straightforward - you show up at the designated spot at your assigned time, if the bus arrives within a few minutes, and takes you to the airport with few or no stops, that by my book woyuld be good service.
My parameters for service generally are about the trip from the airport to the resort.
How long after you got off the plane were you at your resort. I would classify under an hour as excellent service, around 1 1/2 hours as average service and anything over 2 hours as poor service.
After you checked into your resort how long before your luggage arrived. My definition of excellent service would be within 1 hour. I'd call anything under 3 hours average, and more than 3 or 4 hours I'd classify as poor.
Please add some specifics to tell us about your "great service" statement. Thanks.