HotU is a great expansion to a game that didn't really impress me. It contains the best single-player campaign, the sequel to SotU campaign, that takes your through the Undermountain and Underdark, a favorite place of many Forgotten Realms fans, finally ending in one of the Nine Hells.

You can finally lead two henchmen through the great campaign. The beginning features some returning characters from NWN and SotU campaigns, while the Underdark chapters adds two very interesting henchmen: Drow Assassin and Tiefling Weapon Master. Henchmen have even bettter tactical controls than in SotU and will not resummon their summoned creatures without reason. The dialogs have radically changed and now include narrative text, much like dialogs in Baldur's Gate and Icewind Dale games.

As for content, there are new prestige classes, spells, monsters and a whole new Underdark setting, snow setting and new items for dungeons featured in the Undermountain chapter.