I've played fables 1 & 2. I've heard 3 is pretty stuff so Im going to avoid that one
Fable 3 is alright, actually.
I think the problems many people had was that it made some choices that seemed very "non-Fable", and Peter Molyneux (Head of Lionhead at the time) had maybe a bit too much influence in making the game.
There were a few things that upset people, but the game was still greatly enjoyable.
I think it suffered in one way due to similar reasons as Mass Effect 3. The absolute final decision of the game turned out to be a bit lame.
ME3's decision didn't really pay attention to the many decisions made throughout the 3 games.
Fable 3's decision was a bit of an awkward one in terms of realism, in that it made you make absolutely ultimate never-changing decisions that would make people love or hate you forever. Yet the decisions were in turn actually rather tame and in any realistic world wouldn't have been that severe, considering the circumstances at the time.