I didn't quite have time to chew thoroughly but I very much enjoyed playing through Fable 2. It's a good RPG, well told story and fun gameplay. Just like Fable in most ways but much better done. It's full of interesting and ambitious game design ideas that actually work this time.
As with most games these days it's the side missions and extra colour that are most interesting part. The NPCs inhabiting the world are fantastic. Particularly the AI: every one of the hundreds of townspeople has their own wants and desires, their own opinion and relationship with you. Like Bully, but even better. I found getting married really compelling, particularly as my spouse got woven into the main story.
The NPC AI gives room for emergent gameplay, too. I committed my only evil act in the game after a harlot wormed her way into my house with my husband and tricked me into going to bed with her. Dan was upset at my infidelity so I had to deal with her. I tried leading her away to a private place to commit murder unobserved but my husband heard of my evil deed and he was always a bit scared of me ever after.
Fable 2 also gives you a faithful dog, a cute and useful little fella with whom you have a much simpler relationship. I was surprised at the end of the game to find I was quite attached to him; that attachment plays a role in the narrative, too. There's also a real estate game where you buy homes and stores. Towns prosper or fail depending on your heroic actions, affecting your income, so there's a link between the economy and your questing.
As for the main story, Fable 2 works quite well. It embraces the classic Hero / Chosen One narrative rather than trying to alter it in some crazy postmodern way. The free play and main story alternate a bit clumsily, it's a little too episodic. But the main story episodes are great. And in two different circumstances the game makes a strong break from the traditional gameplay, taking you out of your usual milieu. Normally I hate that kind of thing but it's quite powerful in the context of Fable 2. Can't say much more without spoiling it, unfortunately.
One caveat: the game is buggy. Lots of little bugs you can mostly ignore, also some huge terrible game stopping bugs like quests that fail and prevent you from continuing your only saved game. No doubt the worst will get patched, but it's shameful to see an A-list title released with souch bad quality control. My own heroic story end was ruined by the disappearing spouse bug. I'm supposed to return home to the rest I earned, but my husband had disappeared about halfway through the game not to be found. Hope I didn't miss anything.