I've ran 2 sessions of Pathfinder 2nd Edition so far, and this is all of the feedback I've collected from my players and myself.
1: Goblins should not get a bonus to Charisma. They are hideous, unpleasant little bastards that society still doesn't like very much. I would give them Dexterity and Constitution because Goblins typically live in kind of gross environments out of necessity and would be hardier because they're used to wallowing in filth.
2: Strike, Stride, Seek and a lot of other things are awkward terminology. My players and I feel stupid saying them, and we frequently make fun of the weird new terminology at the table.
3: Wizards should cast spells like Arcanists. This isn't actually something mechanically wrong with the system, but I hate how they have to meticulously plan every single casting of their spells. I loved the freedom of being able to prepare a small pool and cast from that. I think it creates a smoother play session where the wizard can prepare a situational spell like Knock or something without completely freezing up a valuable, and limited, spell slot just to use that one spell, if they happen to come up against a locked door.
4: you should be able to drop items held in both hands as a single action. It doesn't make sense to have to use two separate free actions to drop the item in one hand and then the item in another. it's silly.
5: I feel that the duration on positive and negative effects should both last until the end of the turn. It feels pointless to make them resolve at different times, and it adds a small extra bit of confusion.
6: Why do creatures hiding in darkness treat creatures in lit areas they can see as 'Concealed'. that's weird. If I'm hiding in the shadows of the rafters, I don't have a hard time seeing the creatures in the well lit room below me.
7: I feel that you should be able to perform activities over multiple turns at the risk of being attacked and losing all of the spent actions. For instance, you could start an activity that takes 3 actions using the last action of your turn, then on your next turn finish it with the first 2 actions of that turn, but if you take damage you have to roll concentration or something to not get distracted and lose it.
8: You should put how far you fall in one turn. I know it's a long distance, but the question "How far do you fall in 6 seconds" is something I've asked a lot, and I feel like you could just put it in there really easly. It's nearly 600 feet or something.
9: You should bring back equipment kits. They're a great way of getting all of the equipment you need without having to meticulously comb through the lists. I don't know why you removed them.
10: Ball bearings. Add them to the game. They're like Caltrops that trip you instead.
11: the Sleep spell says "The target falls asleep" I feel like this should state more clearly that the target "Gains the Asleep condition" for clarity's sake.
12: HP recovery while resting, as it is currently written, would only heal a level 20 character with a 10 constitution by 1 HP.
It's current wording states that you heal a number of hit points equal to your Constitution Modifier x your level (Minimum 1), meaning that if you have a constitution modifier of 0 or less, you will only ever heal 1 HP, no matter how high your level is.
The minimum value you heal should be equal to your level, not 1.
13: I find it weird that you don't get a feat at first level.
14: My players feel that monsters being able to strike up to 3 times a round makes them too dangerous, and increases the chance that they'll hit (or critical hit) by sheer volume. Most low level monsters that I've run so far don't do anything other than attack, meaning that they would logically just attack as many times as they can manage, and the one fighter has to take most of those attacks because he's the first in to the fight.
This also means that a low AC, low HP character, like our Wizard is at extreme danger because a goblin has a much higher chance to hit him multiple times than the fighter, who has more HP and more AC. He could realistically die in one round of a goblin running up to him and hitting him twice.
15: Bulk is not a good system. It's far too abstract, and the number is far too low. Every one of my players, including the fighter, feel that they're being artificially limited by the Bulk system. They each can carry about 1 weapon, a piece of armor and a piece of adventuring gear. My fight has a Whip, a Rapier and his armor and he's at his weight limit. My cleric is much the same.
Also, a dagger should not weigh 5 - 10 pounds, so it shouldn't be a bulk. it should be L.
I would double the bulk limit, as it currently stands it feels far too low.
16: The wording on Afflictions is weird. It states that "On a successful or critically successful saving throw, you are unaffected by that exposure to the affliction. You do not need to attempt further saving throws against it unless you are exposed to the affliction again."
This came up in response to the Fungus room in the first adventure section. It leaves a lingering cloud of spores, and the wording of this paragraph implies that if you walk into the cloud, breathe the spores, and make your save that you shouldn't have to make the save again, no matter how long you spend in the cloud.
That sounds ridiculous, and I'm pretty sure that's not how it works, but the wording suggests that it is.
17: 3 action Heal doesn't increase with your level. 1 and 2 action heal recovers HP equal to 1d8 plus spellcasting modifier, and that increases to 2d8 when heightened. 3 action heal does not gain a benefit from being hightened.
This is a problem given how much damage enemies can deal because of how many attacks they can do in a turn, and also makes 3 action healing a waste of time when you're higher level.
18: The layout of the book isn't great. Spells should be at the back of the book, where they always have been. It makes it easier to find the spell section when you're looking, and it prevents Spells from taking up almost 100 pages in the middle of the book.