I just got back from two weeks at Pop. My opinion on the buses is the same as ever: good, but not perfect. We had our car with us, but found it just as easy to wait for the buses. Part of that is having three kids to toss in the car, and also, after driving once to each of the non-MK parks, we found that we were being parked relatively far from the gates despite arriving before park opening. At every park, we walked past big swaths of non-handicapped parking on the way to the gate. It kinda took some of the bloom off of the "driving to the parks" rose for us.
I honestly don't think we waited more than 20 minutes the entire trip, with one possible exception. That's park openings, mid-day resort jogs, and fireworks runs. When things go wrong, though, it gives you those stories that make it seem like the whole thing is a mess. One morning, we were headed to MK. We got to the bus stop about 45 minutes before park opening; the line was already spilling out of the queue and extended down close to the entrance to the adjacent Epcot stop. When we walked up, I told my wife, "I'm not worried about the line, I'm worried that there are no buses already here working on the line." I think it's really hard to estimate waiting time (it always feels so long), but I'd say it was about 10-15 minutes before any bus showed up for MK. In that time, a bus for DHS showed up probably less than five minutes after the last DHS bus. It came to pick up ONE woman. By the time an MK bus showed up, the overflow from the queue literally stretched the entire length of the bus stops area (past Epcot, DAK, DHS, and Disney Springs stops towards the 80s). Even then, it was probably about 25 minutes until we were physically on a bus. That is definitely one area they could improve... I'm pretty sure there was one of those Disney Transport spotter people walking around before that "extra" DHS bus showed up; there should be a mechanism in place so that the DHS bus that showed up to pick up one woman who had been waiting less than five minutes could switch places with an MK bus that was on its way. It's somewhat incomprehensible that this doesn't happen more often. In our case, it would have helped to alleviate another problem-- when buses finally showed up, there were two MK buses waiting at one point behind the first MK bus, unable to load passengers. If the DHS bus earlier had switched to MK, and one of those MK buses was now a DHS bus, it would have smoothed things over greatly (not for that one woman going to DHS, but she still would have gotten a bus in 10-15 minutes).
On the whole, though, I had a great experience with the Disney buses. It even convinced me to leave the car in the Pop parking lot.
thanks!