We used Murray-Hill in January of 2008. Their service was good overall, with a few minor issues.
When we arrived at the MCO, the driver was not there for our "meet and greet." He was 30 minutes late. I finally went down one level and found him near the car rental counters. He said traffic held him up. While waiting for him, I tried to phone Murray-Hill but only got a voice recording. We had a "grand gathering" sized group with small children, so the uncertainty and delay were a bit bothersome. Also while waiting, a CM from Magical Express noticed our dilemma and offered to take us to POR. The Murray-Hill guy showed up just before I took ME up on its kind offer.
All went smoothly after that. The driver was polite and helpful. We had our grocery stop at a Publix. Got to POR without any more problems.
Their equipment is a bit worn...vehicle, toddler seat, baby seat, umbroller...but useable.
On the return trip, the driver was once again late picking us up, but this time by only about 15 minutes. He was friendly, helpful, and courteous, like the first fellow. They had suggested a 2 hours before flight pick-up time. But after their tardiness upon our arrival, I changed it to 3 hours. That turned out to be prudent because MCO security was slammed that afternoon. We had enough time to catch our plane, but not much extra.
Overall, I would rate their service as good but not great. I think the issues we had were relatively minor and could happen with other companies. According to the testimonials on their website, many people have had a positive experience with them. Would I use Murray-Hill again? Maybe.
We are going back to POR next January, and I will consider Murray-Hill but am looking at other shuttle services too.
Hope this helps.