I spent three hours there and it felt like three minutes! Bonus-the view of the SF Golden Gate Bridge - amazing! Keep in mind this is not a "Disney" theme park museum but a great look at Walt's family before Walt to present day.
Really worth every penny and a great way to visit the Presidio too.
I am only giving it four-out-of-five because it is hard to get to if you don't have a car, but well worth the trip. Find a way to get there!