I've used ME twice, last July, it was pretty crowded and I had a bit of wait for the bus to the Allstar Music. The bus not only included the allstar resorts but also the POP, 4 value resorts...needless to say there were alot of people in line. I had just missed getting on one bus and had to wait about 15 to 20 minutes for the next one. From the time my plane touch down to the time I got to check in a the Allstar Music was just over an hour and a half.
My husband and I used ME in December, going to the Poly, the lines for the buses were not any where near what I had experienced in July. We only waited about 10 minutes for the bus, the Poly was the first stop, from the time our plane landed to the time we were checking in at the Poly was just about an hour.
I am using ME again for my trip this May. It's free and they seem to have worked out the bugs.