My family has taken advantage of the Disney transportation system on every trip. From the Magical Express bus that picks us up at the airport and takes us to our resort, to the buses that provide transportation for Disney resort guests to and from the parks.
Depending on the time of year, resort, and even bus stop that you're waiting at, your wait time for a bus will vary. If you're at a resort with multiple bus stops and your stop is picked up last, you might see a bus or two drive right past you because it's full. That's frustrating when you're anxious to get where you're going. And if you're at a large resort such as Pop Century, where there's only one bus stop (but lots of people trying to catch a bus), you may also have to wait for a second bus because the first one fills up before your portion of the line gets there.
While some people complain about waiting on a bus, I use the opportunity to relax. I've never waited more than 20 minutes for a bus at any Disney resort but I've heard complaints from others who say they've waited longer. During busy seasons in Disney there's usually a Disney employee at the bus stop with a phone talking to someone at the dispatch station and making sure the buses needed at each resort arrive.
Make sure if you're heading to a dinner reservation to give yourself enough time to get there. Ask any cast member at your resort and they'll gladly suggest how early you should leave to make sure you arrive on time.
Everyone's idea of a long wait is different. I'm pretty patient and I like the Disney bus system enough to keep using it again and again. It sure beats driving!