Oh, don't get me wrong here. I am a ZOOM freak! However, I think in WDW that a bit wider is better for most shots. I am not too fond of ultra wide like under 17mm. I think that many of my shots that I took in the parks other than AK were shot at around 24-50 mm. I think I would have been a bit handcuffed by only having a 50mm, myself. But for the record, it will work just fine.
My copy of the 50mm is real nice. Took me awhile to realize that, as I wanted to shoot EVERYTHING at f1.8, but when you play around with it enough and use it at around f5.6 to f8, it is REAL sharp. It worked well for the night parade at f1.8, but again, I thought it was a bit too zoomed in. I would have preferred something wider.
Being that I am more of a nature photographer, AK was heavenly. I could break out the 70-200 with my 1.4x converter and shoot away. That is where you REALLY need the focal length.