(spoilers) My reaction of MK based on the multiple POV videos:
I really thought the lava bowser projection was a physical AA! There are many little moments that blew me way. Even something as simple as the AR confetti at the end really adds a lot to the ride. I think this will be a ride you will want to do over and over and over again. I enjoyed the rainbow road scene and how they did the transitions. So much magic created with all the combination of technology.
I am not surprised by the slow physical speed of the ride. Do I wish there was more projection mapping on the track to give the illusion of speed? Maybe. But they would also have to do more screens on the walls so I think they had to compromise.
I read a review that pointed out my one disappointment in the ride; It feels cramped and claustrophobic. In the game the tracks and environments are so bright, open, and expansive, I wish the ride was on a larger scale. For example the Shanghai Pirates ride has so many large open areas (only mentioning it because of scale, not comparing the ride systems).
One little improvement they could make would be to add projections to the floor of the finish line scene to blend the floor with the giant screen.
But, I don't want to dwell on the negative because it's amazing what they did. The entire land is wonderful, It must be very surreal to walk through that environment in person.