What Jim said about the cruise line shuttle is exactly what happened to me a couple years back. I was off the Sovereign Of The Seas at a little past 7am and the first person in the bus. I was excited because this meant I might be able to rebook an earlier flight instead of waiting to my scheduled 4pm flight out of Orlando. Instead I sat on that bus for over an hour while it slowly filled up, and I got to spend the day cooling my heels at the airport.
Taxi is the way to go.