Even if you end up absolutely hating all three official campaigns (which I'd consider very unlikely in itself), there's so many great user-made modules that you're bound to find enough material that you enjoy to make it a very worthwhile purchase. So you have nothing to worry about.

for user modules you can always take a look at http://nwvault.ign.com/View.php?view=Modules.HOF by the way. those are the best (as chosen by the community). That site will keep you busy for quite a while :)
also, don't be afraid to play nwn online with people - some might be newbie friendly (or at least not overtly hostile).

I have to disagree there, I've found Morrowind to be one of the deepest experiences I've ever had in computer roleplaying. The lore and the world of the TES series are developed in incredible breadth and detail, and Morrowind especially excels in the visual design as well. The storyline and quests are only a half of the experience, the other half is getting to know the world and its history. And I have to disagree about the flat NPCs as well. Or have you forgotten that unhinged mage boss, the pathological liar god, or the wizard with a harem of opposite-sex clones of himself and a cellar full of zombies?

no it was awful, became too boring.

We at GOG should do the campaign together.

I'd definately be up for some multiplayer D&D action.
My only problem is I don't currently own NWN.

I would too but I don't have a computer capable of running the game

There are several better games available on GOG.

So far my biggest dislikes are the UI and the path finding when controlling the character manually.

I considered mentioning the judge quest, but felt that one good quest couldn't weight up the rest of the game. The "outdoor" areas were actually pretty atmospheric aesthetically, if I recall correctly, but the dungeon part of the quest was as bland as it gets. The writing makes it a memorable quest, however.
Another quest I recall being somewhat memorable involved shrinking down and exploring the inside of a small artifact. If I recall correctly the writing was on par with the rest of the game, but the area design appealed to me. I think a lot of sheer drops and mixed terrain palettes were used to make it feel almost non-generic.