When we flew and stopped renting a car we started using Magical Express and then of course Mears. Really no issues/except for maybe being a few minutes late picking us up or getting to the airport a bit early. Have never waited more than 20 minutes to be taken to resort. Yes, it might make a few stops to drop off or pick up - but again, not pressed for time. Always arrive at MCO by 9:30 am or so.
Now that I am solo for half of my trips, I like it even more. When I travel with my kids/grandchildren, they don't mind Mears. My son who drives there and arrives a day early before his family,used to pick them up at the airport (he does not fly) and now the family tells him not to bother making the trip and take Mears.
Everyone will have their own opinion. I think it depends on how often you go, number of people, do you need to make a grocery stop, want to get there and back quick with no additional stops.