Tesla 2019.28.3 brings small improvements
My Model X, Pensive, recently updated from 2019.28.3 to 2019.28.3.1. As with most four-part-version releases, this is intended to fix release bugs and possible oversights rather than introduce major changes or new features. So far, I have not seen a marked difference with the 2019.28.3.1 release. 2019.28.3 itself felt familiar, and more an iterative improvement than anything novel, which is actually a refreshing change.
Autopilot Behaviour
With 2019.28.3, Autopilot has again improved, changing its behaviour and generally presenting a more reliable experience during the time in which it is engaged. That's clearly a lead-in for the counter-points:
while AutoPilot is generally better at holding the rode, it will throw back control if it doesn't think it can keep control
releases autopilot with force on the wheel
shadows are more likely than before to confuse AP, causing it to abruptly slow or stop
more likely to go straight again at "confusing" curves1
The previous minor release brought a more aggressive AutoPilot which was willing to leave the lane as long as it thought it could follow the line it had set around a curve. This has lead to some harrowing games of chicken coming around curves. I've found 2019.28.3 to be slightly less confident: while it will continue to attempt the same manuever, the car is more likely to release AutoPilot without warning. When I've had my hands in a natural driving position (which tends to apply additional force during these turns), the sudden release of course by the car has tended to be over corrected by the force of my hands which are no longer facing any counter-force. This can feel quite scary2; I've found a more relaxed grasp of the the wheel to be more important than ever to allow grabbing the wheel when AutoPilot disengages, but without applying any inadvertent force.
Looking back at the AutoPilot changes, the current version reminds me of 2018.20 which started to allow for a choosing and following looser lines around curves. It has some similar failures at the same time. One new thing is that, while the news is full of examples of the car crashing into parked vehicles, I've only just now really begun to see a problem with my vehicle nearly driving into things like landscaping trucks parked in the road. This may be happening most regularly in shady areas; parked pick-ups off to the side of sunny roads have instead tripped the emergency breaks. Shadows generally are causing more problems, with sudden breaks in tree cover causing abrupt application of the breaks3.
Nag Notice
I'm not entirely sure when it happened or even if its just the result of small tweaks which built-up over several versions, but the nag notification has become less annoying on highways than when it was introduced in 2018.26. As recently as 2019.28.3.1, the alerts still seemed to fire in unexpected times (such as low-speed stop-and-go traffic), but at-speed on highways the alerts tend to be more reasonably paced.
previously seen with 2019.12.1
it's a sensation like losing traction on ice at first
There seems to be correlation here, unlike the random breaking of 2019.12