Taking a look at the WoTC official material from D&D beyond and the monsters manual anyone can see that they made a pretty good depiction of the creatures
I sometimes wonder if people do know how D&D5E´s creatures, uniforms and the city of Baldur´s gate actually look like before making comparisons...
The problem is the color palette that makes very unrealistic, unlike BG2. The demons are very cartoonish in BG3
Regarding the look of characters:
__ I think there is some disharmony to put grassy-wood, blue sky, red demons (tieflings) in the same picture.
They could adjust colors, so they mix well with the environment, or make different kind of tieflings to different area.
The characters and monsters you meet, the armors they wear are also part of the artwork and should match with the scene, so it feels right. Matching them with the lore is secondary.
It was an early stage version, so probably they will change coloring till release.
At character creation window the characters are still incomplete and "pretty" like dolls,
but origin characters look way better, so probably they will still adjust the "faces" and make them look cooler.