The added content pretty much makes this a "Director's Cut" of Fable.
You'll find yourself going through many of the same areas, quests and meeting a lot of the same people, yet The Lost Chapters adds more quests, emotions and other things to expand upon the first Fable without taking anything away from the first Fable. I gave this a 9.5 due to the new stupid rating system, I would say The Lost Chapters only slightly edges out the original perhaps by .1 or .2 from the score I gave the original. I still go through and play the original and when I need the extra content I reach for The Lost Chapters, all in all it's great if you've never played Fable and want "the best" or even if you just want The Lost Chapters for the extra content because you loved the original.