As with all RPG's you are able to create your own character from different classes. I myself play a mage that is kind of friendly, but to wise for his age. He has a secret mission: to conquer the world en to lead it. The other classes are: fighter and rogue.
The interaction with characters you meet within the game define your quests. There is an overall quest to defeat the Darkspawn. Some ancient evil from the past that has come back from some dark place.
But before engaging in the final battle you can play all kinds of mini quests. I accepted, for example, a job to kill all the spiders (really big ones) from the mage’s storage caves. And I died within a few minutes, for I did not prepare myself enough. Now I am looking for a fighter to help me. As a mage I am too venerable in battle.
Another mini-quest I play is helping a mage friend from the mage's tower as the first enchanter wants to "tranquil" him. And make some kind of zombie out of him. He still lives, but has no emotions or desires in life. I must admit that I (accidently!) told the first enchanter about this escape plans. So no I am between two choices: help my friend, or please my boss. A tough decision I have to make.
The most fun thing in this game is the interaction between characters. In time you get your own party with about four characters. And it seems that they disagree about anything and you really have to persuade them to follow you in your quests.
Anyway, I am only playing this game for a couple of nights now and I am completely hooked-up. This game is a must-have for all RPG minded people out there that still can find the time to play computer games.