And the game is just as solid as ever. This is the end of the Baldur's Gate series, and it definitely goes out with a bang. You can think of
Throne of Bhaal as consisting of two major additions to the content of the game--a new dungeon that you can access from
Amn, and a number of new Chapters that occur immediately after
Shadows of Amn is completed. That's not counting the gameplay tweaks, of course, which are many.
It's hard to give a basic storyline bit here, because people who haven't completed Baldur's Gate II all the way don't want their experience to be spoiled, and I can sympathize with not having a couple of hundred hours to throw at a game. Suffice it to say that the storyline of Throne of Bhaal is as entwined in the Baldur's Gate mythos as any of the titles, and your adventures as Bhaalspawn bring you deeper and deeper into the whole mess. Some of the nasties that you meet are very, very nasty. Everyone's talking about the dragon, and for good reason.
Fortunately, there's enough to talk about outside of the plotline. There's that added dungeon I was talking about, Watcher's Keep. It's huge, and it'll take up many hours of your time, but it does some very neat things with the Infinity engine that make you realize that the old beast still has some life in it. It's also damnably hard if you're not prepared.
To make the game even more expansive, the experience cap has been busted to eight million XP (!!). This means that many characters can get up to level 40. Frightening, neh? Along with the severely expanded level range, you'll find a number of new abilities to play with as your characters advance past level 20. Things like special attacks, new 'tenth-level' spells, and awesome priestly magics will make every AD&D gamer tingle with delight.
And the wild mage. I actually own a copy of the Tome of Magic, where the wild mage was introduced as a PC class, and I have to say that actually playing one in a game is just as amusing as running one for a character. Their magics are, well, wild, unpredictable, and usually quite intriguing. You may not want to attempt to complete the main adventure with one, but it's a lot of fun to play around with.