...Yeah... that's gonna be a no from me, dawg.
If Hulu is any indication, I doubt the audio/visual experience of this service will be up to par. Obviously it will be inferior to physical discs, and given Disney's track record with Hulu, I am sure it will be inferior to versions of that Disney content that were distributed by Amazon or Netflix, too.
I'll be sticking with my 3D or 4K Blu-ray versions of these Disney/Marvel/Star Wars movies. I have a 4K TV that can also do 3D and a 12 speaker Dolby Atmos surround sound system. Who the heck wants to watch a bitrate starved Marvel movie in pancake mode with stereo audio?! Hulu's audio may be the worst thing about the service. It uses 64 Kbps AAC stereo audio and it sounds like trash. The lack of 3D support though, is a deal breaker. The Marvel movies and some of Disney's animated releases like Tangled, Wreck-It Ralph, and Frozen are among the best 3D experiences out there; they lose a lot when you watch them in flat mode.
As for the Disney/20th Century Fox/Marvel content that hasn't been released on Blu-ray -- I still highly doubt that the versions available on this service will be superior to the up to 15 Mbps 1080p H.264 copies with 640 Kbps E-AC3 5.1 audio copies of that Disney material distributed by Amazon and Netflix.
Also, I can't see how this can be useful as anything more than an "add-on" service to one of the big boys like Netflix, because Disney has said that "PG-13 material" is going to be the limit. One can only handle so many superhero movies before they want to watch something like Game of Thrones or The Walking Dead.
So in summary: I'd rather watch superior copies of all of this content from my own personal Disney + -- my Plex server -- than this inferior service.