I'm looking forward to the new areas to explore and NPC's/monsters to encounter. Also looking forward to the Mods .
I don't know how in-depth the tools will be, if there will be any at all, but there is so much value in letting players use BG3 to create new stories. With a large enough community and enough access to the engine and its tools, we could be getting entire campaigns with cinematics and voice acting in the years to come. Or it could be like previously, and we'll get custom class mods. I guess that's nice too.