This is a weird release. For reference, I have an AP2 car. I just did my regular work commute out of a combination of boredom and curiosity. I did notice the nags were slightly more prevalent, but they weren't as bad as some people's apparently are, so that's good.
The cars show up in adjacent lanes, but it's not really consistent. I was in the far left lane. The lane to my right was separated by double white lines, and it didn't show any cars in the adjacent lanes. My guess is that it only shows for what could be considered a legal lane change. Seems like an odd decision if so. It was also pretty janky in general (I watched the display show a car slowly slide out of my lane and into the lane to my left). I hope it gets a lot of polish sooner rather than later.
My drive has me changing freeways in a sort of half circle exit (think a pretty wide u-turn), and on 2018.18.2 (and earlier, I believe) my car handled it fine. This release continues to handle it, but the lowering of the set speed limit is a nice touch. I approached at 70mph, it gradually slowed me to 35mph for the turn, but then only increased my speed back to 65mph. It also skipped the normal nags and jumped straight to beeping at me immediately into the curve. That bears further investigation.
It also skipped the nags and jumped straight to beeping at me on a straight, almost empty street as I approached a stop light. It only did it that once, so I sincerely doubt it's the start of stop light detection.
Aside from all that, the usual quirks of the system still exist. It'll follow cars through coned off construction lane changes, but won't do it without the lead car. There's a gentle curve that it still can't manage (it skips staying in my lane and jumps to the right). Speed limits are still wrong in a lot of places.
It's a hint of progress, but not much.