If you booked a package with your agent, you may not have much choice in cancelling.
I agree with the other poster that it is a toss-up for how long it takes.
When at the airport, the van will not leave until it is full. So since it holds 8-10 people, and let's say you are a party of 3 then they will not leave the airport until 6 more people get on board. If you are lucky, they will be headed in the same general direction as you. If not, you may be stuck going to their destination first before yours. Just adding on how much time it will take to get to your hotel. I also agree that I have always had friendly and knowlegable drivers, so not a bad experience just not as efficient as I would prefer.
If you can change your mind, you may look into getting a towncar. About $80 round trip with a free grocery stop. Check out the transportation board for reviews on the various companies.
If you're "stuck" with Mears, relax you will still have a wonderful vacation!!
Brenda