Fable III is one of those rare games that I enjoyed despite a plethora of bugs and oversights. Lionhead has created a bug report page. Here's a list of the problems I encountered, not all of which are bugs, in hope that a patch might improve the game.
Jasper quit talking to me halfway through the game. Thankfully, he exists more for comic relief than to progress the story. It's not an audio problem. There was no animation suggesting that Jasper was trying to speak to me. He simply stopped commenting in the sanctuary and did not say anything at the story's end (as I saw in a friend's game) either. In the sanctuary, I can press "A" to ask him to explain the room I'm in, and he will simply stare at me. If I walk up to him, he turns toward me. He just won't talk anymore. I've created a second character to see if this bug repeats.
A couple times in combat, the option offered to me as Up on my D-pad was not my Slow Time potions but transportation to the Road to Rule. Twice, my combat was interrupted as I was transported there.
The stats page was broken, last I checked. It showed "0" weapon upgrades (I had a fully upgraded hammer), only 8 quests completed (less than half of what I had done) and only 9 potions used (again, less than half of the real number).
Graphical lag (as common in solo play as in co-op) is frequent and terrible. It happens at day and at night, in multiple zones. It happens while walking/running around, and apparently not (that I remember) during combat or in the sanctuary... but I might be wrong about that.
In playing in another's game in co-op, my character doesn't animate while moving half the time. He's fine in combat, but stands still and glides while walking or running.
The "back" button is not used at all. Why not use every resource? Personally, I would like it to provide a shortcut to the quest list.
The quest list does not keep my place when I use "B" to back out of a quest description. I have to scroll down past the story quests again to view the relationship quests I was looking at. A minor annoyance.
There is no "Repair All" option for rented homes. This is a major annoyance when the player owns many properties. What could take just a couple button presses is turned into a boring five-minute chore.
There is no "Buy All" option at stores. So buying 10 health potions or 10 sacks of grain at a time requires twenty button presses instead of two.