It was absolutely godawful. Like painfully bad. In fact, it was some of the outright worst writing I’ve ever seen in an videogame, much worse than dubiously-translated Final Fantasies from the late '90s and early '00s in fact. It read it like it had been translated from another language, by a guy whose like, third language was English, but you considered himself incredibly funny/witty in English, but totally wasn’t. Which I think is kinda what happened.
With DOS2, if you’re playing it now, you’re not even looking at the original dialogue for DOS2. They re-wrote the dialogue for the Enhanced Edition, and whilst the re-writes are far more extensive in the later areas of the game, everywhere got some re-working.
For me, though, it was out of the frying pan, into the fire, writing-wise, and everything I’ve heard about BG3 suggests that writing sausage is now deep in the coals of the fire, being burned to a crisp. Specifically, in terms of NPCs they went from the “wacky jerks and lolzy weirdoes” of DOS1, to DOS2 with “everyone is either terrified /cowed or a cunt, no alternatives”, to, from multiple articles (Ars, RPS, Eurogamer, etc.) saying BG3 is just straight up “everyone is a cunt, period”.
This is sadly familiar from tabletop RPGs. There’s a certain kind of DM, often one who puts quite a lot of effort in to the setting, who, for some reason, just makes literally every NPC into a total cunt. I’ve never understood it myself, but it’s not uncommon, and I’ve seen pen and paper adventures written that way too (as well as a couple of other CRPGs).
All that said DOS2 would have been quite fun (because there’s so much you can do, generally) if it wasn’t for the combat - which is balanced on the assumption that you’re upgrading like all your weapons/armour on all characters about every other level (no overstatement), and is very much about, as you say, gaining as much of an advantage as possible early-on, because of the way the turns are taken.