Hey there. Former naysayer (maybe hater) of PF2 here to give my perspective, even though I've come around to it - actually preferring it to 5e at this point.
There's a lot of conditions - too many for my liking, actually. You'll want Foundry to apply the math if you're doing it online or use the condition cards if you're doing a physical game at a table. It tells you what the effect is and reminds you to apply it.
The situational bonuses don't come up as often as I expected they would. You've got the equivalent of a +2 bonus if you're attacking a prone or flanked enemy (that's been in the d20 system for 20 years). You've got magic item enhancements that are always there. You've got spell effects like Bless (which are true in any edition). In my experience, other situational bonuses just don't come up often enough to really bog down the game.
The tightness of the challenge level math is a real issue if you're using pre-written adventures. The default is more challenging than I like to run. So I would design mostly Low or Moderate encounters - Severe encounters I would be hesitant to use with the exception of a boss that the party has had time to research weaknesses/immunities beforehand and have a clear way of escaping. The other challenge levels (Trivial or Extreme) I just wouldn't use.
If you're using a premade adventure, run it for characters one level higher than the suggested range - at least until they have learned good tactics and some system mastery. It can be brutally challenging. (I was running their first AP - Age of Ashes - and by the book we were averaging a TPK every other session, and this was with 5 characters instead of 4.)
The Multi-Attack penalty tripped me up at first, but I got the hang of it after a couple sessions. It's a vital part of the 3-action economy, which I think is one of the biggest selling points of PF2.
As for resources I'd recommend: there's a good content creator on YouTube called The Rules Lawyer. He has a series contrasting 5e and PF2 and gives lots of advice for players and GMs. Here's an example of a first combat. If anybody wants to do a quick 1-2 hour session of a PFS Quest on Foundry, give me a shout. It would probably be easier to explain in an actual game than on a message board.
There's a lot of conditions - too many for my liking, actually. You'll want Foundry to apply the math if you're doing it online or use the condition cards if you're doing a physical game at a table. It tells you what the effect is and reminds you to apply it.
The situational bonuses don't come up as often as I expected they would. You've got the equivalent of a +2 bonus if you're attacking a prone or flanked enemy (that's been in the d20 system for 20 years). You've got magic item enhancements that are always there. You've got spell effects like Bless (which are true in any edition). In my experience, other situational bonuses just don't come up often enough to really bog down the game.
The tightness of the challenge level math is a real issue if you're using pre-written adventures. The default is more challenging than I like to run. So I would design mostly Low or Moderate encounters - Severe encounters I would be hesitant to use with the exception of a boss that the party has had time to research weaknesses/immunities beforehand and have a clear way of escaping. The other challenge levels (Trivial or Extreme) I just wouldn't use.
If you're using a premade adventure, run it for characters one level higher than the suggested range - at least until they have learned good tactics and some system mastery. It can be brutally challenging. (I was running their first AP - Age of Ashes - and by the book we were averaging a TPK every other session, and this was with 5 characters instead of 4.)
The Multi-Attack penalty tripped me up at first, but I got the hang of it after a couple sessions. It's a vital part of the 3-action economy, which I think is one of the biggest selling points of PF2.
As for resources I'd recommend: there's a good content creator on YouTube called The Rules Lawyer. He has a series contrasting 5e and PF2 and gives lots of advice for players and GMs. Here's an example of a first combat. If anybody wants to do a quick 1-2 hour session of a PFS Quest on Foundry, give me a shout. It would probably be easier to explain in an actual game than on a message board.