How I wish I owned this lens... Clicking the picture takes you to its Flickr page, where you can find a length to a Disney Photography blog post I wrote on Creative Focal Lengths (and also read an addendum to said post in the Flickr caption).
Nice rental for WDW trips but it is heavy so you need a good tripod and head to hold it. ; I used it for Fantasmic! using my tripod as a monopod and got great results. ; As this photo shows, it is a very good portrait lens and is used by pros for that purpose. As you indicated, with any lens, it takes time to learn how you will use it. ; I would say, in the future, you would find buying this lens a good investment.
I carried it, the Tokina 10-17mm, Tokina 11-16mm, Nikon 50mm, Sigma 30mm, SB-600, along with two Luxi tripods all day every day while we were there. ; All told my bag weighed over 20 pounds with everything in it. My back hurt a bit afterward, but it was well worth it. I had no problems holding it with the Luxi F and the Manfrotto 486RC2 (basic ballhead). It was really difficult to pry myself away from the UWA and Fisheye at night. ; However, I'm glad I did. ; I plan on purchasing it someday, but right now (unfortunately), cars, a house, and other necessaries come first. ; I am really hoping my uncle lets me borrow this lens again for our Christmas trip!