I picked up Baldur's Gate: Siege of Dragonspear on sale, and I've played a character through Baldur's Gate so I can run him through SoD. I'm still early in the game but it's not bad thus far. Basically more of the same sort of thing, with a few twists here and there. The one issue I've had is that my original party is unavailable, so I've had to recruit several companions who join as first level characters. (Minsc and Dynaheir, for example, who I didn't recruit in the first game just for a change of pace.) The combat has been fairly challenging, and seems to be balanced for a full strength party at the PC's level. Fortunately there are ways to grind through the early battles using items acquired during the first game.