(Wizards underpowered)
From reading a lot of discussion on the Paizo forums, there seem to be two things that lead to this impression (and note, that is not me saying that its entirely incorrect, just that whether it is or not it seems so for these reasons):
1. In general, spellcasters have been cut back some from 3e era ones. That's because (and I know this doesn't go over well with some, but I don't know any better way to put it that is honest) they were out of balance with non-casters. That was just taken as a given by a lot of people and was viewed as somehow okay by many, but that didn't make it good design and one of the design choices in PF2e was to push the two types together. One of the areas where this is very visible is that spellcasting is generally a weak way to directly deal with a single opponent--and that's probably the single most visible sign of effectiveness that most people percieve. Spellcasting can still be a good way to start cooking up groups when a spell caster is willing to take some positioning chance, and good ways to buff and debuff (but as I noted, people who haven't internalized the importance of manipulating crit and fumble chances don't always see it that way), but neither of these tends to be as visible (and of course occasionally you'll get GMs who make it really hard to apply the first; personally, I've watched one players lightning-oriented sorcerers dump more damage out on a semi consistent basis than either of my fighting types did, she just doesn't do it all in one place).
I recognize that you are not necessarily endorsing the first point here, but I do feel it is pretty dismissive. I didn't play 3e or Pathfinder, so it simply isn't the case that I am so used to high powered wizards that I don't recognize PF2 balancing act. The argument also cuts both ways: it is just as arguable that PF2 designers, after a 15 years of wizards being overpowered, overcorrected and made them weaker than other characters.
For what it's worth, here is my argument that wizards are underpowered (as mentioned, I played a wizard for levels 1-4, though a couple of other commenters, notably Zapp, have indicated that they feel wizards become competitive at level 9, when they get access to 5th level spells).
Let's consider the restrictions on wizards compared to other character. I make the point here and I will make it again afterwards:
restrictions are NOT a bad thing. My problem with wizards is not the limitations on them, but rather, that the spells in PF2 are not sufficiently powerful to compensate for the limitations on the class.
1)
AC: Wizards are one of the two classes (along with sorcerers) that are not proficient with any armor (well, half of clerics as well). Neither wizards nor sorcerers are a Dex primary class either. Depending on their Dex, they are between 2 and 3 points below regular armored characters (characters who can hit both their armor and their dex cap), and 4 or 5 points below either the specialist armored characters and characters with a shield. The disparity can be reduced by 1 using mage armor.
2)
HP: Wizards and sorcerers start with 2 hp less than the "standard" classes, and 4 hp less than the "high hp" classes (6 hp less than barbarians, but that's fair). The effect of having low AC and low HP is magnified in a system where opponents can take multiple attacks in a single round and have a sliding scale to crit.
3)
Limited weapon proficiencies: Yeah, even sorcerers look at wizards and point and laugh.
4)
Limited resource spellcasting: Casting is a limited resource. At low levels, it is an extremely limited resource.
5)
Vancian casting: You prepped a variety of Will, Ref and Fort saves and only fight one type of enemy that day, you will be ineffective. You prepared some utility spells and run out of combat spells, you will be reduced to cantrips. This also means that playing a wizard (or any prepared spellcaster) is more work than playing other classes. You are taking time to learn your different spells, create spell loadouts (or make them on the fly).
6)
Reliance on the Recall Knowledge minigame: The Recall Knowledge takes an action. Often in combat. Maybe you'll succeed, maybe you'll waste your action. Maybe the rest of the party will help...nah, they're spamming attacks. This is a big deal because...
7)
Virtually all of your spells take two actions: Note, in a game whose selling point is the 3-action turn, it is extremely frustrating that wizards essentially are the 2-action class. The only thing that is more frustrating is complaining that wizards are underpowered, having people argue that wizards are not underpowered by pointing out the slow spell (which on a failed save removes one action from the creature for 1 minute) and realize "Hey, that means that if the monster fails his save, he has the same number of actions as me!".
8)
Spells seem designed in a redundant fashion: Auditory and visual illusions are two separate spells. An illusion that changes your appearance is a 3rd spell. An auditory illusion is a different spell than throwing your voice. You need a separate spells to change the magical aura of an object. Detecting magic and reading auras is two separate spells. There seem to be an extremely large number of spells with niche abilities. This affects wizards at two levels: first, you have to spend money (and have downtime) to actually learn the spells. Second, you need to prepare the spells in specific slots (or spend more money on spell scrolls). (This issue also affect sorcerers).
Once again, the existence of limitations on a spellcasting is not a problem. I specifically chose to play a wizard because I wanted to try Vancian casting. However, in order for limitations to be worthwhile, spells need to be sufficiently powerful to offset the limitations. Frankly, for cantrips, 1st level and 2nd level spells, this is not the case. We were in a fight, and I had saved up my highest level (2nd) spell slots. I'm using my highest spells in a clever way, correctly targeting enemy weaknesses...and barely keeping pace with the fighter next to me. I'm thinking "after this fight, I'm wiped, but he can keep this up all day, has a much better AC and hp than I am, isn't the party just better off with a second fighter?".