A decent action-RPG
Fable II is an improvement on its predecessor in most ways. While it still fails to be a true AAA RPG, it's an enjoyable experience as long as your expectations aren't too high.
As with the first game, the combat is lacking in depth, but can still be fun and provides a bit of variety. The ranged weapons are definitely more fun than they were in Fable, and they integrate nicely with melee combat, allowing you to switch back and forth easily.
Spellcasting is a disappointment. The need to charge your spells to attain full power is frustrating and makes playing as a pure caster character very irritating. There's little reason to sacrifice melee abilities in order to gain superior casting power.
The story is an improvement over the first Fable, but still feels lifeless. The focus on the main character as the player's avatar prevents any other characters in the game from having any personality to speak of. Cities feel like boring carbon copies, with the citizens mumbling the same four or five lines in the same two or three voices.
Fable II, much like Fable, can be fun to play, but don't expect a serious RPG experience. If that's what you're looking for, look into Mass Effect or one of the 360's vast lineup of JRPGs.