We could nitpick about what is really an open world game and what is not, but BG3 is definitely not AT ALL like BG1 and 2, Dragon age Origin or Mass Effect either.
Probably the closest comparison I can think of is NWN1 campaign - just erase transitions between different bits of the map. Outside D:OSs of course, that used the same structure (and narratively suffered from many of the same issues. Once again the map consists of multiple, separate zones with little thought put how characters in zone A would react to proximity of zone B. Shockingly, BG3 is not even that bad, compared to what we had in D:OS2.
Yeah and I'm absolutely not saying that everything is bad in BG3.
In exemple in my opinion the underdark is mostly fine.
If you remove all creatures it look like an entire area build as a whole rather than pieces of a puzzle (the story) glued together.
I really hope the rest of the game is gonna be less like the surface and more like the underdark. I guess it was easier for Larian to design the underdark because you can really explore it the way you want while there's a path to follow on the surface.
That said, in my opinion they could have made better choices for the surface both to limit the narrative issues and create a more coherent area.
