Stripped down version of Fable II that is disappointedly easy.
Everything that you loved in the first two games have been streamlined and boiled down so far in Fable 3 that you wouldn't know you were playing Fable unless you read the box. The most notable thing is the leveling system, which has been oversimplified to the point of almost not existing. You purchase abilities with seals that you earn while playing, but unfortunately you can only buy abilities at predetermined points in the story line. Half the fun of the Fable franchise was going out to earn xp to buy better abilities at your own pace, not waiting for the game to ration them out as you play. Fable 3 forces you to wait until a major plot line is finished before allowing you access to the new chest on the Road to Rule, which are opened with Hero Seals for new abilities.
If you hated the Magic system of Fable II, you will DESPISE Fable 3's horrible system. Not only is there no magic bar, your hero must equip magic gauntlets in order to cast spells. Unlike either predecessor, you are limited to only 1 spell at first, with 2 at the max. The game does allow you to merge the powers together for combos such as electric fire, but players who like playing as a caster can no longer count solely on magic. It is simply stupid and a huge step backwards.
The co op is much better than Fable II, (it would have to be), but as the hosting player does all of the cutscenes and quest triggers, the 2nd player is basically just running behind the host, not doing much of anything except waiting.
The combat is basically the same, but since you can't really specialize as melee, ranged, or magic, you will get very bored, not only with the first play through, but each subsequent play through will play EXACTLY the same. You can make different decisions on a 2nd game, but it isn't much different, and most players will likely get bored after finishing the first.
Finally, Fable 3 has the stupidest menu/inventory system I have ever seen. Instead of having a proper menu in which to equip and use items, pressing start sends you to your "hideout". In different rooms you will find your gear, clothing, items, settings and everything else you would see in a menu. It is cumbersome, time consuming, and an overall waste of time.
In general, all of the RPG elements of the original Fable and Fable 2 have been stripped down, presumably to cater to a new audience of younger players who will buy and play it only because they don't remember how great the original Fable was. Fable 3 plays more like an action game than an RPG. It seems like the developers of the Fable franchise don't listen to players, and just do whatever they feel like doing, much like a mad scientist who is only a genius in his crazy mind.