As someone who's been heavily involved in online NWN play since it came out, let me weigh in with a few opinions.
First, I totally agree with the critiques of the official campaign (OC). I only got into Chapter 2 before I got bored and shelved it, never to return. This was a week after I bought the game.
That said, there are already several thousand user-created modules available for download at Neverwinter Vault. As always with such things, most are... shall we say, "limited"? But among those are several dozen single-player mods that are quite excellent, with story, dialogue, NPCs, henchmen, custom items and monsters, etc. NWVault has user ratings and only rates a module on its "best of" list if they manage to get 10 votes. There are a number of fine conversions of TSR/WotC modules as well (I played a conversion of TSC that was quite entertaining for a few hours of play).
But NWN truly shines in multiplayer online play. Regardless of what the box or Bioware claimed, this game was always intended for this purpose (this assertion is based on extensive reviews of what the designers and others said in press releases and on the Bioware message boards both before and after the game's release). If you have a group of friends with the game and at least one broadband connection (for the host), you can have a computer D&D experience that is stronger than any online RPG to date (IMHO). If you don't have the friends handy, there is a great community at
www.neverwinterconnections.com (NWC) where you can find games or like-minded players to game with. Players and DMs are rated and given feedback so you can get an idea of what kind of fellow gamers you want to play with.
I prefer to run campaigns since you get the character-development and sense of camraderie that you get from PnP games. Since the game came out I've run several campaigns at NWC, the longest of which has gone over 5 months and about 20 sessions now.
The toolset is fairly easy to work with although scripting is required for the more complex actions. When I started I knew nothing of C++ or any other computer language. The online community and the messageboards have thousands of scripts that you can easily adapt to serve virtually any purpose (check out the scripting forum at the Bioware Official Boards). I have produced 6 extensive modules, including 2 that are up on the Vault, that have custom monsters and extensive scripted effects.
Now that the game is 6 months old, I still run my campaign game once a week but have shifted focus to newer games like BF1942. NWN is the first of a new generation of online RPGs, and is the best simulation of PnP D&D (i.e. the group of players sitting around a table gaming, NOT the single-player adventure that we get from games like the excellent Baldur's Gate series) that we have thus far. If you want to play online D&D with other people, I strongly recommend it.