Expect to be blown away.
You know how all of us like to imagine what it would be like if the Imagineers got the time and budget to do something special? Well, Alcatraz is going to be the result. This is finally Imagineering's retort to Universal's Spider-Man and Forbidden Journey. It's like a checklist of everything you've wanted in an attraction (LPS based RVs, BIG sets, good ride length using multiple floors, projections, animatronics), special effects, elaborate queue, etc.).
I've taken to calling it the "kitchen sink" ride as it has had everything thrown at it.
Internally, the goal of this project is to make the best attraction that can be made with modern technology.
I'm sure that once it opens their will still be those prefer Universal's offerings (I'm still partial to Spider-Man as it more seamlessly blends the technology together over Forbidden Journey), some will still like Mystic Manor for it's modern take on a classic Disney dark ride, and some will like Sunken Treasure for the water based RV (I have yet to get to MM or the new Pirates). Regardless of what attraction you might prefer, Alcatraz will be technically a technical marvel in its scope.
While I don't mind sharing specifics about Big Bird, I think it's best to keep as much of Alcatraz a surprise and cloaked in mystery for now. I'm hoping Disney does the same. It should be a real treat once it opens and shouldn't disappoint.