Now I'm not even going to put any other amusement park up to WDW in quality and stuff, but there are some things you can compare it to,
I went to a park here in KC today called Worlds Of Fun, and being a Disney snob I had to comment. You really appreciate what WDW offers and the experience when you go to other parks.
The customer service in WDW is so off the chart when compared to customer service at WOF. I have gone to WDW many times over the last 20 years and have had maybe 2 bad experiences with people that work there. In one day at WOW I have at least 5 encounters where someone was rude, or just disinterested in helping out.
WDW is either older or at least very similar to WOF and it is crazy how they look. WDW looks like it was opened yesterday, so shinny and brand new. WOW is run down, dirty.

I can definitely see why Walt built his own park after witnessing how others are operated.