Honestly I can't really think of an Obsidian developed art direction that was great (or even good really) since they turned into Obsidian.
I really liked MotB's art. But yeah, I don't play Obsidian games to be blown away graphically.
Though I don't really understand the hate for DS3 in this area specifically, IMHO it's their most graphically impressive game -- and one of the nicest looking games in its genre overall, with some great animation, effects and lighting.