I liked the story and the 3.5e implementation, but the Aurora Engine and some Gameplay flaws (at least in my opinion) like the Death-System (even if it got somewhat better in SoZ), the crafting and the inventory fiddling killed most of the fun and I only managed to finish the campaign once. That being said, I mostly played (a lot) on persistant worlds - multiplayer engine (even with all its bugs and flaws) really being an outstanding feature of NWN2.
But I'd love to see it redone with a more polished engine and revised gameplay features, best maybe with isometric graphics, I actually never liked the 3D graphics of NWN2. But keeping it on the 3.5e Ruleset would probably be an issue of licencing.
I would be happy to back. Obisidians involvement in NWN2 is one of the main reasons I am so eager to play PoE.