I received 42.2 over the weekend (upgraded from 39.7) and this morning was my first chance to test it during my daily commute. My initial impressions...
Lane changes are much more decisive. I don't know if this change came in 39.7 or 42.2 but I had previously found lane change to be more of a "can I avoid dropping out of AP to change lanes?" than a reliable feature. I had resorted to only using it when traffic was very light and even then it sometimes would just let me sit there in the lane with the turn signal on. I used it today several times and it worked without issue.
With 42.2, AP also suggests lane changes if traffic is lighter in another lane and also for lane changes needed to take exits (if you enable Nav on AP). I have the setting for speed based lane changes set to "Mild" and AP suggested only a few lane changes. I'll try "Average" on my next drive but I'm guessing "Mad Max" might suggest lane changes a bit too frequently.
I'll need to try my morning drive again to be sure, but it seemed that the Navigate on AP feature was suggesting a lane change to a lane that was 'exit only' before my desired exit. This was at the start of my drive so it may have been traffic related lane changes; I was still trying to figure out the notifications popping up on the screen. Will try to verify this the next time I take this drive.
Not sure if this was posted already, but the Nav on AP lane changes are shown in blue vs regular navigation steps.
Of these four steps, I only took over for the final merge. I'm not sure if AP would have handled that fine but this merge to the right is into a lane where there were cars approaching and attempting to merge into my lane. May need to try another time to see if AP can handle it.
One thing that pleasantly surprised me was how AP handled the exit from I95S to I676. As shown below, I was in a lane where you can keep left to remain on I95 or keep right to exit. Up until 42.2 I had to disengage AP so that I could keep right and exit. Not only did AP keep right but it turned on the right turn signal! Maybe that's in the release notes but it still elicited an "Oh wow" from me.