Basically, from the current reviews (not "previews", REVIEWS) Fable can be described as thus:
Overhyped. It is, essencially, not all that it was hyped up to be. That is because Fable was hyped up to be the Ultimate RPG - and frankly it's not.
However, don't go thinking that that means Fable sucks - it is still an incredibly excellent game, just not as perfect as was envisioned.
Where are the reviews?
Anyway, I can't wait to play it. Having met the lovely Big Blue Box guys, I hope that they succeed. I doubt that it'll be exactly as they said, but it'll still have the most freedom out of any game to date.