Gameplay is very similar, for obvious reasons. Wrath has more things, of course, but it's still based on PF1e.

All the Mythic Path stuff makes you scale extremely fast at certain points, but it's not like you're suddenly doing different stuff in combat. But if you like to use super hard hitting spells, you can sling those for days (I'm level 15 and my Angel Oracle has like 80 spells slots between level 1-8, and some other characters aren't far behind).

If you're ok with just spending all your spell slots every fight or something, then rest, and go again, then very few fights should take long, but I'm the type of player who usually doesn't rest inside of dungeons. Although I'm maybe a bit too stingy with them, that's why this one dungeon took so long (I also didn't really optimize my party a lot, but did some changes for the last few fights, that made things a lot easier).

As for the writing, I'm the wrong person to ask, I don't really care about it, same as with Kingmaker. I'm playing these games for the combat, which I mostly enjoy.

If you're not sure about Owlcat games after Kingmaker, I'd recommend you check out Rogue Trader, if you're ok with the Warhammer 40k setting (which I didn't care about). I found it very enjoyable and a lot less buggy than the two Pathfinder games, although it is on the easier side.