I’m sure the experiences vary greatly due to many factors. Like where you are and on what highway driving habits etc.
For me it just hasn’t helped at all. I used it almost everyday for several weeks before finally just giving up and going back to regular AP. It just can’t manage the highway system and quick lane changes needed to drive here in downtown Fort Worth or Dallas.
I did not mention in my first comment that I have been testing it for weeks now in the urban highways that I commute on every day (Pittsburgh) and it's also been both useless and dangerous. It has absolutely no way to deal with the density here and the quick multi-lane changes that are required at interchanges, plus the often poorly-marked lanes. I had been hoping that if I put it in a nicer situation (namely, expansive, flat, straight midwestern interstates) it would do better. Well, it did better, but still nowhere near useful and often dangerous due to sudden movements that are surprising to other drivers. All of the thing it got right were things that I could have easily gotten right myself (and with much less stress), and the things it got wrong ranged between annoying and frightening.
It seemed that for roughly 50% of exits that I was not taking it wanted me to change into the left lane "to follow route". But there is no need to be in the left lane in order to not take a right exit. And then it would suddenly apply the brakes when that right exit came. And then on the other side of the overpass, when the lane merged in from the right, every single time it would swerve over to the right to center itself in what it identified as a very wide lane. I had to take over every time to avoid looking like a drunk.
On top of that, V9 has regressed in simply keeping stable in the lane -- it wobbles very subtly left and right, which was also common in earlier versions but they had it straightened out (literally and figuratively) by the later V8 versions. This constant wobbling becomes very noticeable on long highway drives and my daughter, who is prone to car sickness, became quite nauseated.
And yet, Musk is talking about finally launching an autonomous ride sharing Tesla Network in 2019? He is either knowingly lying or he is completely disconnected from reality.