I still haven't beaten act 3
Freeing Gith price, defeating Jason' Isaac's character, finishing Wyll's and Astarion's quest is all that's left
.

I liked act1 the most - it is easily the most content rich, and polished of the three

Didnt' like act2 aside from
gith creche and finale
.

As such act3 seems like a step up for me. Couple issues:
I think it fails to pay off on promises made throughout act1&2. Story threads are continued, (tieflings, hag/Maryna, companions) but they are minor, and in some cases retcon, or contradict choices we made previously (Hag being the most outrageous one). Forunately for me, I wasn't invested in act1 story, so I am more than happy to see something more Baldur's Gate like, but as the whole the story feels disjointed.

There is multitude of issues with reactivity - that's started for me as soon as I left EA area, and haven't stopped. Act3 might be worse, as there is more story content there, but it hasn't been worse than act2 for me. Most quests, seem fairly straightforward - that said, I thought there was only one truly complex quest in act1 (goblins vs grove), so the rest of the game being rather straightforward doesnt' surprise me. A lot of magic has evaporated for me after act1 - with skills like speak to dead/animals becoming underutilised.

A lot of combat encounters in BG3 do come down to gimmicks. I don't think they are bad, but I think some of them are poorly set up.
Iron Throne specifically required careful preperation, and I think the game should have prepared the player for what is coming. I had to restart every major encounter in act3 (Iron Throne, Orin, Raphael, Sarevok) - I wouldn't call them hard (maybe aside from Iron Throne depending on how many prisoners you wanna save), but you need to play them in a very specific way to succeed. For example, when I entered encounter with Orin, I simply didn't have enouth AoE attacks prepared. Once I fixed that, the fight was easy to do
. Fortunately, my bard is crowd control oriented, and Hypnotic Pattern seems to be a solution to almost every late game problem.

I really like the feel of the city, but I am not a fan of being contained to it. To me, the city work best as hubs, the way they were done in BG2/Deadfire. However, considering Larian's structure, I am impressed by Baldur's Gate. However, they have a lot of work to do, to improve the reactivity as it falls apart big time in act2&3. Individual quests feel underwhelming. The game peaks in act1 and the rest of the game lives in its shadow. Still, it could be much much worse. It probably will be - I hear things about the finale of act3 which don't sound great.