I seem to have gotten over my KOTOR addiction for long enough to have a solid crack at Hordes Of The Underdark. I've played it for the last couple of nights, and gotten to the end of the First Chapter. Now that I've gotten past the silly memory puzzle with a 'colour pool' (WHAT?) and some chains, things are shaping up nicely. My Blackguard, Nico, has hit Level 21 and is now "Epic". Now we're in the Underdark, I'm getting to do some really nasty things, including slaughtering a Matron Mother and massacring an entire Mind Flayer city. Which is nice.
Overall, HOTU is much improved on both the original campaign, and the first expansion pack Shadows Of Undrentide. Expect a proper review on State fairly soon. Otherwise, if you've got NWN and SOU, but not this yet, you should definitely consider it.