It's probably the most China thing I've seen America build in the last few years. Bold, covered in LEDs, techno-optimist. Vegas in general is proof that America can build as fast as China in the right social and regulatory environment.
The Sphere show is a preview of what retina-resolution VR will look like. When you look at the screen, things simply look real. I believe that once VR gets this good, people are going to spend hours a day in there.
The seat you sit in matters a lot. Most of the content is nature / organic curves, but as soon as something rectilinear shows up, you can immediately see the distortion. If you sit near the center, it's tolerable. If you sit near the edge, it's not.
The "Postcards from Earth" content is visually stunning, but the story is distractingly preachy and incoherent; they would have been better off removing all the voiceovers and replacing it with ambient electronica. (In the story, a super-advanced future human civilization capable of large-scale space settlement chooses to abandon Earth because they still can't solve climate change. Like really, you put 10^9 tons of mass into orbit and you still can't scrub CO2 from the atmosphere? Hard disbelieve.)