The maximum viewing area is less than 1080p. It’s a sphere, so you’re only seeing a portion of the video screen (about 1/3). The example in the video is about the best you’re going to see from the THETA S streamed over mobile. I think it’s a realistic representation of what you can expect.
You’ll get better quality with the THETA V, which is 4K. I sent a note to streambox to see if they’ve tested their cloud encoder with the THETA V. I am still waiting for a reply.