I just finished my first play through of Fable 3 and I don't think I really need to say more than "I don't see a need to play through a second time" but I will (obviously.)
Fable 1 I played through 4 or 5 times, Fable 2 I played through a dozen times. Fable 3 - I don't know what I'd do differently. I made millions, overthrew the tyrant, kept all my promises and then did a bunch of nice stuff that I didn't promise. I married my childhood sweetheart (Elise), had two children then adopted all the orphans in the orphanage, beat the big bad guy without any civilian casualties and finished the game with millions in my account and the treasury. There are a few side quests left and I might re-visit my kingdom but why would I start over? Maybe if Lionshead comes out with some kick a** DLC, but even then it would have to be really good - better than Knothole Island and See the Future - both of which were little more than extra, and sorta boring, side quests.
I also won't pre-order next time. This isn't the game we were promised. It was (for me at least) much faster and shorter than Fable 2. There may have been more acreage to explore, I don't know - I did a ton of wandering and there was nothing to see (except maybe a few dig spots.)
We were told that we would be able to pick up, hug and toss children, we can't. In fact your "relationship" with your family, your dog and the villagers is much, much more limited in Fable 3 than it was in 2. You can't entertain the crowds any longer, you can interact with one villager at a time and the ways you can interact with them are much more limited. You can't hand out gifts really. You are limited to two children per household (I hired nannies and set up extra houses for all my adoptees.)
In short Fable 3 is a major leap backward on almost every level. Not a good leap backward as in more like Fable 1 but a leap backward in the sense that the game is a little less than either of the other games in almost every way, in some cases it's alot less.