I visited Beijing for a little over a week in 1991. Half the time I was forehead-smacking astonished. The rest of the time I was facepalm flabbergasted. I'm guessing that Chinese visiting the U.S. for the first time have a basically similar reaction.
I also learned to fear crossing streets in front of a solid wall of oncoming bicycle commuters. There'd be very little left of a person after being run over by a Beijing bicycle stampede. I haven't been back, so I don't know if that's changed in the last 20 years.