I went to Prince Charles Theatre in London for their first showing. It was also packed. It looked and sounded great. That said, I didn't notice any massive improvement over the Blu-ray restoration. Maybe it was the projector or I'm not really able to pick up on the difference between 1080 and 4K (though it's not actually 4K if that technical memory is correct?).
Did anyone else pick up on anything?
Listened to your latest podcast today and heard you mention this.
I'd imagine unless you have them side by side, you'll be hard pressed to tell the difference between 1080p and 4K in the theatre. Even at home, that might be the case. The closer to your TV you sit, the better it will be. But don't despair, HDR is far more noticeable than 4K and cinemas can't do that yet. Do your research before buying a 4K TV - you'll see a lot of cheap ones claiming to be HDR but you need to have a 10-bit panel for true HDR. OLED is the way to go if you want deep blacks but it'll cost you at least a grand in the sales, Prices go down substantially towards the end of the year.