It is indeed fantastic open world action-adventure...but that's the thing, for most part it's open world action-adventure. As open world (or otherwise) RPG, it's nowhere near as good. No wonder a lot of RPG fans don't even consider it to be an RPG (I'm not one, as I said, I find it to be THE edge case between action-RPG and action-pseudo-RPG).
I don't find comparing it to Larian's work is really flattering - their games are good, or even great at certain specific things, but as actual full-fledged CRPGs they are quite lacking and pale in comparison to subgenre pinnacles like Arcanum, Planescape, Fallout 1/2, BG2 and some of the Ultimas (which Vincke is so fond of, and eventually he might just get it right).