Doesn't take itself too seriously
There are better RPG's out there, such as Oblivion to name just one but Fable stands well on it's own and even though the main storyline is short there are many other things to do so you'll probably breeze through it in around 25-30 hours.
All in all this is a game that isn't to serious, Oblivion is far darker than this but Fable is lighthearted and fun. There are some downsides though.
Character interaction is really shallow, you can't decide what to say like in other RPG's which is a real let down because you never really get attached to any of the characters in the game, even ones that you are married to!
Also the combat engine is a little easy, once you reach a certain level its very unlikely that you'll find an opponent as strong as you are, with the exception of bosses.
If you like fantasy RPGs then I recommend this one!