Almost impossibly brilliant!
Your characters role in the world is completely customizable. You can be a thief, mage, merchant, adventurer, arena fighter and so on. You can steal pretty much anything from clothes to food from their cabinet. You can talk your way into receiving better treatment or bribe people for what you want.
The games Fame and Infamy system is great and can be rewarding. The PC modding community has created even more hours of game play to be had and even some eye candy for the adults who want it.
In total this game would have been a 10/10 but the fact that I didn't feel any obligation to the main storyline was a bit of a disappointment. I felt that they could have done a better job of making it sound more urgent because the world was ending.