So here are my thoughts on both games:
Check the official website for references on what I'm saying.
FC2 basically breaks the boundaries that games can't be realistic enough (thats not to say that its perfect, merely that its ahead of almost everything else).
When you get cuts (I mean medium sized ones, not scrapes) you'll have to actually bandage them, if they're big wounds, you'll have to perform surgery.
Another interesting thing is that if your bones break, expect to snap them back on like you see in the movies.
Also, you must see the fire. Its the closest thing to real life fire, the forest burns, it burns until the fires are doused out or there is nothing left to burn. There's a lot of wild life in the game, and the whole idea of being able to set a fire to destroy an enemy camp is brilliant.
Also the developers may include the need to sleep, eat, and drink, they've said that they would. But if not, thats what mods are for haha.
The sheer amount of detail they've put into the game is amazing.
The game is now comprised of 12 regions, each bigger than the original Fable's entire Albion. in other words? You've got more than 12 times the original game.
Some interesting features include alignment no longer being just black and white (there is now purity and corruption, cruelness and kindness, evil and good), terrain that will change according to your actions in the game (say you killed of bandits attacking a camp, you come back two in game years later to find that the camp has turned into a village), the dog (which morphs along with you), and the family.
The best thing I think? Fable 2 isn't about doing things this way or that way, rather the game is about consequences. If you're evil throughout your life and have a son, consequently, your son will be a devil child. If you kill a bunch of people at a camp in the wilderness, when you come back, that place will remain unchanged, maybe overgrown but it would not develop.
So your thoughts?