For me:
Easy to use
Magnetic timeline, no need to bother with patching or assigning tracks
You can choose what to output with the range tool and roles
EX: Output self contained movie with titles in English or Spanish
Great organizing
Ability to build custom effects, generators, transitions and title stuff in Motion
Better media management then old school FCP
In addition to some of the sites listed earlier you may want to check out Ripple Training, Steve Martin (not the actor) and Mark Spencer, a contributer on here in the Motion forum, have really great material. It is a one time purchase not a subscription based model. I also ordered Resolve training.
As others have pointed out there is a bit of a learning process but really is not that difficult.
My only beef is no native support for the Cinema DNG format. Hoping that will change in the next version.