Probably. It's free, what have you got to lose?
But honestly, its a very average game. Fable 3 has good voice acting....and honestly, thats about it. Combat has been dumbed down to 1-button spamming, your character doesnt change as a result of how you 'live' as much as in Fable 2, the story is very average (some characters are either criminally underused to appear to serve little purpose) and arbitrarty leaps and bounds that would have stuffed up the plans and strategies of 95% of the people playing it, and the "Good/Evil" choices are even more silly than they were before.
Its the sort of game where you have far more fun trying to pick out which VA did which character. So is it worth it for free, yes. You'll get a few hours of enjoyment out of it, then put it away and never feel the desire to play it again.