The Most stand out feature with fable is that the world was really well simulated. From NPCs behaviors and dispositions, to the economy of the world. The NPCs aren't as scripted like characters in other RPGs. They react to you more like the people in "Sims." If your liked enough, have a guard or villager "follow" you and help you on your quest.
The Economy was unbelievable as well. You can buy everything and make money from it. Decide what to charge for goods, and how much to charge for rent. And it all effects what happens in the town. Once you have the money, buy a bar and charge nothing for drinks. Just see what happens.