I think act 3 has loads of promise. I enjoyed it hugely despite all the bugs, but it would obviously be much better without them.
It was overwhelming on first reaching the city, but then I get that with other cRPGs too, and I found that if I just started chipping away at the quests it got manageable quickly enough. I thought that on the whole the quests were interesting and varied, rather than a whole bunch of fetch-quests, and exploring Baldur’s Gate was amazing.
I agree that there were some quest lines that I’d liked more of, especially the hags, though admittedly
I never found Ethel again in my playthrough, as I was doing it without any guides and clearly missed something. From a note I found, I’m guessing I need to watch out more carefully for some mushrooms next run! (Don’t tell me, I want to find her for myself

)
And I definitely agree that the epilogue was a let down, and I really wanted all my party and key NPCs to get a look in.
But if bugs are fixed and epilogues expanded, I’ll probably think Act 3 is great. And if, on top of that, some of the quests/storylines that feel like they might have been truncated were fully developed and the quest design tweaked in a few places where I did find it frustrating, I reckon it would be a triumph.