It's all a personal choice IMO. We love the Disney strollers because they are much easier to navigate than the average umbrella stroller. They have a nice big canopy and big wheels that make for a smooth, (almost) effortless push.
We went with friends on our last trip. They brought a stroller from home and someone took it by mistake outside Kilamanjaro Safari. Disney gave them a stroller for the rest of the day and they have since said they will never do anything but rent Disney's from now on.