BioWare has listened carefully to its fans and has made sure to include more of what players want. For instance, fans of Baldur's Gate II's player strongholds can use Throne of Bhaal's improved version: the "pocket plane"--a small fold in the fabric of reality tended by an ancient imp with a talent for smithing magical weapons. And fans who enjoyed solving Baldur's Gate II's countless side quests and puzzles should also enjoy tinkering with the Machine of Lum the Mad, a legendary artifact with a series of buttons and levers that can produce all sorts of random magical effects that may bestow protective magical resistance on your favorite character or blast that same character to smithereens. And like the previous games, Throne of Bhaal will feature cameo appearances by famous characters like the sage Elminster and the mischievous wizard Volo as well as the fearsome Demogorgon--one of the most infamous, dangerous, and evil monsters in the history of Dungeons & Dragons.

And the other, containing some spoilers, resides at FiringSquad. Here's an non-spoiling snip:

Throne of Bhaal will conclude the Bhaal Saga, and is played in two parts. The first is the add-in part, which will be tacked onto the main Baldur's Gate II game with a new dungeon and a few new monsters and toys, including the Machine of Lum the Mad. From what we saw, this part seems to be pretty much complete and locked down.