I speak as a CharOpper ("Character Optimizer") who really enjoyed 4e.
First, I speak of 5e. 5e hates me and all my kind. 4e was effectively a game written only for players who were into character optimization and tactics. 5e was a backlash to that, and it roundly rejected almost all of the character optimization game.
PF2 isn't like that. PF2 will let you bring your full CharOp skills to bear. It has all sorts of widgets to mess with (at least one feat per level, every level, guaranteed) and if you do it just right, you can eke out... maybe a 10% to 20% advantage over the person sitting next to you who walked in the door knowing nothing other than the fact that they wanted to play a dwarf with an axe. The advantage to be gained is there, but it is thin. You can play for it, and win it, but the result won't be game-breaking. From a game balance standpoint, PF2 is amazingly well-balanced. Among other things, almost all of your character's basic math comes from your statline and your class, so as long as you get decent stats for your class, it's basically impossible to make your character outright bad. (Admittedly, it's entirely possible to make a character that's decent on paper but that you can't play well, and some classes require more player skill to play well than others. It's also possible to create a character that doesn't really fit with the rest of your group. That's not the same as the character being inherently weak/bad, though.)
It also has a lot of complexity at the tactical level, but the important thing to bear in mind is that that complexity is different. "Good tactics" in PF2 look very different from "good tactics" in 4e. Characters that try to dial in on a single plan and iterate as hard as they can (which was basically the 4e ideal) will find that they're weaker than they should be. Keeping your eyes open, having a few viable options, and adjusting to the situation as it goes become much more important. Having figs on a grid is still very, very important.
The class roles are not explicit in PF2, and while you can still find traces of them, they're not nearly as strong. Champions are pretty much defenders, especially if you build for that specifically. Clerics and bards have a fair amount of leader to them. Wizards are definitely still doing the controller thing... but most classes (and most builds) aren't nearly so specific. A lot of it blends. Now, you can (and probably should) arrange for complementary characters in the party, and you can absolutely get some useful synergies there, but a lot of times it won't be "one leader, one defender, N strikers". It'll be "I'm good at inflicting grab/prone, so I have synergy with a rogue." or even "As a grapple-monk, at level 6 I can get Whirling Throw. That's going to synergize pretty well with the Sorceror getting Wall of Fire at level 7."
Now, it's not the same number of decisions for the fighter and the wizard in this one. The wizard does have more, because we're back to more or less the same vancian casting that every version that isn't 4e has... but the fighter still has quite a lot more decisions to make in PF2 than they do in 5e (or than they did in 3.x).
Finally, and this is important, PF2 is far less wacky than a lot of other editions. Like, in a very real way, it's following in the footsteps of E6. Unlike 4e, which starts at heroic, and then goes to paragon, and then goes to epic, PF2 starts at heroic, and... mostly stays there. Your characters tend to get more heroic as you go, but... well, for example, the absolute earliest that it's possible to get permanent flight is level 13, and that's with a race that's GM-approavl-only. The earliest that it's possible with only "Common" options is lvl 14, and that's with a specific class and some notable feat investments, and even then you only manage it by having a flying mount. Things like permanent size gain are hard. Things like damage/debuff auras and major opportunity attack shenanigans are hard. Silly 4e paragon tricks like radiant mafia or having every one of your attacks slide and knock prone for free are functionally impossible. You can get some cool stuff done, and you eventually do get to the point where you can go murder an army on your own if you have to... but you'll be doing it one sword-swing at a time. The stuff that you could get in 4e by being sufficiently cheesy doesn't exist at all in PF2.
Still, it's really amazingly well-designed... and the entire ruleset is available for free online. If you're curious, I'd encourage you to read it.