Icewind Dale helps continue the Baldur's Gate story alone, in an ice land far to the north.
The gameplay is great as you advance your characters through the various quests and missions, building up their strength and powers. The graphics use the same Baldur's Gate engine but are smooth and lush. The music is really great as well, matching the different landscapes you come across. You have a great assortment of special weapons and armor to find, and all sorts of interesting monsters. They have a great use of scale in Icewind Dale, pitting you against tiny rodents and huge giants. You really do worry when you see something very large stalking towards your party!
The game is relatively linear - you know what your next set of quests are and move along through them. But it's a great deal of fun while you do, and you really feel like you're making good progress and able to really customize your party. A great game for people who enjoy the Baldur's Gate style of gameplay.