New beta tester with 10.3.1 (SS 99) and I am impressed, but it's got a ways to go.
Took a 100 mile drive today, and it completed the first 10 miles segment without a disengagement. Then went on the two lane highway and noticed I couldn't effect following distance change with the thumb wheel. I was set to FSD-"average", and I guess that locks the following distance to about 2 seconds which was uncomfortable for me at 60+MPH. Also the car would slow down a few MPH often with oncoming traffic. Got really annoying and definitely not as smooth as Autopilot/TACC.
Anyone else experiencing this behavior?