Personnaly I'm replaying DoS1 and yeah, you definitely understand where Larian is coming from.
The chain system is really a bad system. Characters always walk in surfaces and die. It's worse than in BG3 with surfaces ofc, but it's really a suboptimal system especially in a hard game (chain/unchain very often to place your characters).
The UI is really unresponsive. Better in BG3 too but still really not optimal.
I feel the same with their "no pause" system. I understand that it would be hard in multiplayer to pause the game but you have tons of buffs in DoS, combats may be extremely hard even in normal mode... and you cannot buff yourself at all before any combats. Their solution to go turn base in BG3 is probably better than nothing but you never really have to buff in BG3 and it creates other issues (hide/ambush being particularly OP).
On the other hand, I think that the map of DoS is much more coherent than the BG3 one (theme park). I don't know why they choose to create small areas pasted together rather than a coherent big map. Same with dungeons. There are a lot of choke points you can use in DoS while it's really complicated and very open in BG3.
