The show is recorded in 4K, so whether you're watching in 4K or not, you can rest assured that the most state-of-the-art video recording equipment is being used.
Unfortunately for me, my video stream absolutely collapsed about two-thirds of the way through -- near the end of the last tent segment. Prior to that I experienced a number of small glitches, like words missing. And for most of the playback, I had no ability to pause or rewind the video. I'm watching through an Xbox One, hard-wired to my quite fast broadband service. I had to step up to it and press the power button to reboot and get the show back up and running, and in the end, I couldn't even exit out of the Amazon app, let alone turn the box off with my remote control. So, my first Grand Tour streaming experience went about as well as the celebrities did in the show.
As for the show, I liked it, though some of the tent segments were a bit "forced." Hopefully things will smooth out over the coming episodes.