The game will be awsome, in the same cattegory as Oblivion if not higher. NWN1 used the D&D 3.0 rules while NWN 2 will use the 3.5 rulesets. The game is being created by the guys that gave us KoToR 2 and they, to the delight of many, made the Module Builder way better. The game looks awsome and is awsome.
Its basicly a single player game with a neat(lets hope it is)offline story. Well thats not the thing that makes NWN1&2 stand out, its the fact that with the Builder you can created Persistent Worlds(PW) or Gameworlds, which are like player made MMORPGs using the game.
Players can make anything for the game, just like in Oblivion. But this time Obsidian worked more on the multiplayer aspect of the game so it could rock us for more years than NWN1 ever did(like 4 years its been on and on).
This game may be about fantasy but with the proper mods in can become a Sci-fi game too. You would just need to created guns, and spaceship and lots of sci-fi content for it.
Links:
http://www.atari.com/nwn2/
www.bioware.com