It was quite good both times I was within the coverage area, and I was guessing it might roll out much more widely as a feature of their VR headset (since the data is more 3D than street view's), but no.
There's a big list of places where they're mapping this year [3] but who knows when that data will make it to the actual service.
[1] https://en.wikipedia.org/wiki/Look_Around_(Apple)#/media/Fil...
[2] https://www.apple.com/ios/feature-availability/#maps-look-ar...
They've got 4 cities done in California, which leaves 15 for the other 49 states.
I'm in Knoxville which isn't covered, only Nashville here with Memphis presumably next in line. We're the 131st largest city in the US with about 200k people, similar to Salt Lake City or Columbus. Could be a long time before they get the rest of us.