A combination of PTS incentives and curiosity about the new dynamic encounter system got me to spend some time on the public test server this past week.
My aging PC doesn't have enough disk space to support having two versions of SWTOR installed nowadays, so I had to put the PTS on my laptop, but that actually worked out quite well this time around as I was travelling last week and had the laptop with me for evening entertainment anyway.
Only two planets have dynamic encounters on the PTS right now: Hoth and Tatooine. It's currently not clear whether that's all 7.6 will launch with or whether these planets were picked for focused testing and we'll be surprised with some more content once the patch goes live. There were some indicators on the PTS galaxy map hinting at dynamic events on other planets like Alderaan and Belsavis, but with no actual content available there so far.
One thing I originally wondered after seeing the sneak peek trailer was whether dynamic encounters would be more like World of Warcraft's world quests (as in, personal to you) or dynamic events in other MMOs (shared and the same for everyone). Interestingly, the answer turned out to be "both". There are two types of events, designated as either "group shared" or "encounter shared". In the former, your progress is personal, and the encounter continues to exist for other players on the map even after you've completed it. In the latter, everyone doing stuff contributes to the event's progression, and once the encounter completes, everyone gets their reward at the same time and it disappears from the map. The shared encounters are generally rarer and can still be soloed if nobody else is around, but they tend to require killing more mobs and can therefore feel like a bit of a slog if you're the only person in the area. On the other hand it's a lot of fun (in my opinion) if there are other players around and you can see things progress really quickly as everybody does their part.
In general gameplay terms, the encounters are about what you'd expect: a lot of kill x mobs and some clicking on shiny things, though there are some standouts where the devs clearly tried to be creative and come up with more varied activities.
I don't think dynamic events are intended to be a new "main" gameplay mode, though depending on how many planets will get them when 7.6 launches, I'd be curious to see how much levelling you could get done by just doing dynamic encounters - as an experiment if nothing else! Realistically though, I think they are meant to be similar to side missions, just without all the picking up and handing in required. At max level they currently award a tiny number of tech fragments and Conquest commendations, small enough that they wouldn't make for a great primary source of either currency.
One thing that made me wonder a little was how much focus there is on highlighting these new dynamic encounters on the map. The galaxy map highlights planets that have them active, and on the planetary map they show up as big glowy diamonds. There's nothing wrong with that in principle, but it does seem an odd choice when the devs took multiple steps in the past to hide away exploration missions and/or make them less prominent because they were apparently confusing/distracting people. Surely new levellers will get a lot more distracted by all these big glowy indicators on their maps? I dunno.
I'm still a bit torn on whether to try the new lair boss on the PTS as well or not. On the one hand I prefer not to spoil myself when it comes to content like that and would rather see things for the first time on live, but on the other hand every bit of feedback might help with making the Propagator Core a better raid.
The initial round of forum feedback certainly hasn't looked too good. Players were asked what they thought of the fight's different phases, and everyone basically replied "what phases?" because by all accounts, it was just an extremely long slog against an enemy with a lot of hitpoints while trying to manage some bad stuff dropping on the floor.
There has since been another dev post on the forums that basically admitted that almost nothing about the fight was working correctly and that it will see massive changes with the next PTS update. Which is good in the sense that it means the tedious version people experienced in the first week wasn't at all final, though it also makes you wonder why and how an operations boss ended up being put on the PTS in that state in the first place (since you'd expect the devs to be able to verify that at least the very basics are functioning before asking people to play test). I guess I'll have a few more weeks to see how things develop and whether I want to have a go myself.