Once on the bus it is about 12-15 minutes, and this is the longest ride. Now, if the line is really long they may be counting the time it takes to wait for the bus. When we were there this past New Year's Eve we waited for a bus for about 20 minutes and then the 15 minutes to get to the park. Still not a bad wait.
Getting home at the end of the night can be a different story. Last summer, my sister, my son, and I waited through three busses before getting on the 4th for a return to POR. That was about 35 minutes waiting and another 10 minutes on the bus. Even given this, it doesn't seem that bad.