I've been running the Playtest for two groups, one a monthly Skype-based gaming group that had finished Runelords a couple months before the Playtest came out, and the second a new Tabletop group that just started the game yesterday. Fortunately, I've learned some mistakes from the initial Playtest and went into the Tabletop playtest assuming that rules are likely changed from the first to second editions. While this slowed things down, I found I was justified in this and learned a few things that Paizo likely intended to be learned.
Due to character generation, the game actually got started a bit late, which is why we only finished the initial encounter. Fortunately, I did have the Hero Labs Online Demo which is quite helpful for character generation. This allowed us to develop classes and characters that were fully legal. One player is in both the Skype and tabletop group, and did some decision-making for the Cleric but wasn't there for all of the Skype game so I did some choices as well.
Human shield-and-sword Fighter, Goblin draconic Sorcerer, Halfling wild Druid, and a semi-NPC Human healer-focus Cleric.
The Tabletop group consisted of the following:
Half-orc animal-totem Barbarian, Half-elf tiger-stance Monk, Halfling animal-focus Druid, and NPC Halfling Feint Rogue.
I will admit I made multiple mistakes with the initial Skype-based playthrough. I was still on a Pathfinder 1 mindset and thus I was making assumptions about the rules. I also suffered a bit of frustration with certain aspects because it didn't fit that old mindset... and I have to wonder if this type of mindset might have influenced some of the Playtest groups that have had problems with the new edition.
(To be honest, I came over from DND 3.5 as many did, and thus I've over the years made multiple errors as rules from DND 3.5 did at times change but I assumed they remained the same. This is part of the reason why with the Tabletop Playtest I'm being far more cautious.)
One interesting way that the two groups differed was the first encounter. My suspicion is that this first monster was placed there to showcase the Critical Rules seeing it had a low armor class. I'm not sure if I actually forgot about the Critical Hits (I suspect I did) or if it was just the Cantrip selection of the Skype group... but with one Fighter and three Casters, pretty much most of the fight was using save-based spells like Electric Arc rather than things that actually gave critical hits. Also, the monster managed to take out the Sorcerer first-thing because of poor character placement and only a Hero Point kept the Sorcerer from dying (something that actually happened to the Sorcerer on either two or three occasions, pretty much once each game session).
The Tabletop group differed in a couple of ways. First, there is only one Caster, the Druid, and she is designed as more of a support character - also, she chose Ray of Frost for an offensive spell which meant she needs to roll to hit... and did crit the critter). Second, the Rogue was specifically designed to be a support character and thus I not only kept the 8 in Strength but also went for Feints rather than Finesse, meaning on her critical hit with a rapier, she did one point of damage. Still, the combat lasted only one round this time as when the Barbarian closed to attack, he critted twice and took a critter that was at half hit points and the first attack actually killed it... I suspect if the rolls had been different, the Barbarian (who wasn't even raging at the time) would have killed that encounter.
I took time to look up rules rather than assume things. Thus we learned little tidbits that a 1st edition Pathfinder group might have assumed - you don't have a -4 to hit for firing into combat but instead take a penalty if someone is directly between you and your target. Likewise, you don't add half again of your Strength modifier for using two-handed weapons. This was actually significant as if I'd just assumed, it would have left the game unbalanced.
Looking back at the encounter I have to wonder how the Playtest would work for a group that had never played Pathfinder or DND 3.5 before. If you go into the game with no preconceptions, the game may very well play differently.
The next part of the Tabletop Playtest will take place in a week and a half, at which point we'll likely get close to the end of the first adventure. At that point, the tabletop and Skype groups are going to diverge - with the Skype group I'm focusing on just the adventures using the same PCs (for 1st, 9th, and 17th level) as we meet Monthly and thus have a shot at maybe finishing the Playtest (though to be honest, they MIGHT finish the 9th level part but I doubt we'll finish the final part). The Tabletop group though will move to the 4th level adventure with different characters and we'll see how things play through. And as we learn the rules more, the game should hopefully play faster.