Fable is a rather interesting game as it plays like an RPG combine with the Sims. At it's best it excels in both worlds. At it's worse it's feels neither complete nor polished in both areas.
The game is very slow to get into. I must admit that I allmost stopped playing the game for good after the first hour. The controls felt awkward and the initials tasks and training had no meaning.
Thankfully I kept playing though and I grew accustomed to the controls as the storyline picked up and became meaningfull.
For the RPG side the best comparision I could make it Baldurs Gate: Dark Alliance for the Xbox. It pays very similar to that game only as a pure RPG I would rate it slightly below it.
The game is very linear as you have a main storyline to advance. Like BG:DA the items I recieved left much to be desired. I am not getting Flamming Swords of Troll Whooping and any such interesting items. Instead you get basic weapons like Steel Longsword and you can place Gems into these weapons that give the weapons a magic bonus like +fire. That's about as interesting as items get. Non-weapon items aren't even as interesting as the rather dull weapons. There are no traditional stats for items to raise like Strength or Intelligence.
Also, the game basically allows you to make the RPG no-no "fighter-mage". The game is broken up into three skill trees, one for melee, one geared towards bows and stealth and one geared towards magic. As you earn EXP you can dump it into any of these areas.
One thing I've found that is very annoying is all merchants only buy certain things from you. If you want to sell a weapon you you have to find a merchant willing to take it. This might be fine for a very open game like Morrowind, but in a very single-player linear RPG like this I don't believe it adds anything to the game.
As a pure RPG I'd only give it a 7. And allmost all of that is based on the decent story being told.
But of coure Fable also gives you the ability to shape your character through your actions. I feel this part of the game was way overblown just like Black and White's morality was. It's as simple as killing people you shouldn't kill makes you bad. Killing only the bad guys makes you good. The game doesn't really put you into any tough moral situations where what you should do is hard to tell. Basically, if you want to be evil kill people all the time. Otherwise, leave the townspeople alone and you'll become a saint.
And what I feel is a huge letdown is the the lack of good interactions with NPCs. The townsfolk will constantly say interesting things to you. All you can do in reply is make gestures like flexing or snarling. It would have been nice to have some dialog actions like Knight of the Old Republic to go along with the gestures as it feels rather rediculous to stand in front of people flexing over and over to impress them.
While I sound like I might be trashing the game, I give it an 8 out of 10 as I have found it mostly fun thanks in most part to a decent (though easily guessable) storyline.