This is how Fable was MEANT to be.
Now, finally, Microsoft has unleashed the beast within and this is by far a largely different game than the original Fable. The new content makes it well more than worth it to shell out the bucks, even if it is only $20. Best of all, if you haven't played Fable before, GET THIS ONE. Its cheap, works with the Xbox 360, and will last you hours on end.
The best part if you've played before, is when the game ends, your guy is still uber, still has all the gear you had before except now, you can continue to play within a story line. Instead of senselessly going around towns and slowly "aquiring" each property, you can continue the story line in your uberness! This alone makes up for having to replay the entire original game.
Not a huge upgrade in any other department than storyline though. Graphics, sound, interface, all pretty much the same, which is fine because there weren't major problems before.
Overall a great game that you must play, regardless if you've played Fable before. If you held off on the original and were disappointed because of what it was missing, this game is for you.