Well the 2nd one was pretty good, but had some major flaws. (My personal favorite RPG of all time is TES IV: Oblivion, btw)
Once you beat the main questline in fable (which is good), there's hardly anything left to do except just the extremely boring kill the 20 guards, woodcut, bartend, etc..
The family + houses u can buy was a sweet feature, but even then there was hardly anything in the houses, even the big $1,000,000 mansion.
Aside from the main quest Fable just didn't have much to offer.
The graphics were pretty good, the combat was ok, but i would've rather it had more weapon types and magic was controlled a little differently (took me forever to figure out the control heirarchy scheme on the Xbox 360)
All in all i'd give Fable 2 a 7.5/10. Lots of cool ideas, pretty good main storyline, but aside from that, not much extra content.