As someone who never played BG1-2.
I thought Jaheira was really well done.
I never got the hype about Minsc anyway, guy who acts like a Barbarian but is actually a Ranger that has a hamster? Ok?
Viconia had an impact but felt a bit pointless, could easily just have been someone else. And if they missed the mark on her character like some people here are pointing out, then there is nothing more annoying than that for fans, so maybe they should change it.
Never met Sarevok because of a bug or something, act 3 things... But feels like this might also have been a needless addition.
Berserker was in 2e a subclass of ranger - that is why Minsc behaves liek one. He should have been a barbarian berserker in this game imo.
As for
Vicki and Sarevok: It depends on how you played BG1&2. I never romanced Viconia, so she stayed evil in my playthrough - for me, her character in BG3 fits, but if you romanced her and helped her better her ways, it's not a fit. Same with Sarevok really - BG3 Sarevok fits with me, but not some others, who invested a lot in getting him good aligned and seeing the evil of his way.