Planescape Torment is far better game than Baldur's Gate. The story, the characters, the gameplay, the attention to detail makes this jewel, in my opinion, superior than BG 1 and BG 2.
The story: While in the BG series your character fallows the trail of the clichéd great evil – be the hero, in PT you, the Nameless One, have a lot of personality and mystery that right from the start pushes you forward to find out how and why did you end up in the mortuary. Your body is scared and has some tattoos that provide some hints. There is a lot of dialogue in this game, but it has so much moral complexity that keeps you interested. Your decisions and interactions with other characters are far from good-evil type of thing. You feel that choices really matter to unfold the story. While many think that BG has a great story, it is also true that many parts of it were fillers while you were tediously looking for Irenicus, who was actually a more interesting character than your own. In PT, you really feel attached to the character making the game much more immersive.
Gameplay: the game follows the D&D rules as it is tradition in BG series. The difference is that your characters is always the Nameless One, but you can make him a thief, mage, fighter and choose the stats according to your style of play. Depending on your stats, your class and your choices the story unfolds differently, adding great replay value.
Graphics: even today the artwork is unique and the places you visit throughout the game are varied and well detailed for a 12 year old game. The resolution is not as good as in BG2, but you will still enjoy it and the size of the characters is a bit bigger. Visually, this game is great.
Planescape Torment did not receive the same attention from gamers as BG1 and 2, but if you like RPGs with excellent story and gameplay, this is it.