there needs to be big changes after fable 2 before i would think of buying 3. First and foremost imo is the combat, its so simple, plain, bland, boring and every other simile of these words combined...lvl 3 time lvl 4 raise dead lvl 3 time lvl 5 fire = win. i think the combat should be made more like dmc4, pop3 or assassins creed, still very simple in controls but entertaining to watch and go "yeah...i just did that awesome flip slicer thingy".
Another let down was how long you have to spend serving drinks, cutting wood or blacksmithing to get anywhere, i mean i know you have to start low and work your way up and i know that they cant just give you the money straight out but its just so repetitive and boring.
On a + note i liked having a dog.
OH and another big deal for me was being able to pick what your character looked like...in the end you had the evil guy/girl and the good guy/girl models and that was about it (unless you played multi player). One of my friends played a female character and quit as soon as she became less of a beautiful pure princess character and turned into a giant ugly hulking blue veined freak of nature.