I also have the Fanatec, and it is indeed the best wheel available for Xbox.
That being said...
The force feedback is VERY fake. By this I mean... It uses the same signal that tells any regular controller to rumble, and it makes your steering wheel shake. It is not true force feedback, in the sense that it is actually responding to what you are doing.
Real force feedback controllers are sent MUCH more detailed information, and respond much more naturally. Also, in many cases I have had to turn the forces response down on the Fanatec wheel, because when it shakes it will give the same sense of traction loss for tiny little rumbles, that would be more realistically suited for had you gone off road. Fortunately, the wheel does allow such customization. You can tweak a large number of things, and this allows it work excellently with just about every racing title out there (on Xbox obviously).
If you want to have the best for Xbox, then do get this wheel, but first know that it is WAY overpriced, and it is FAR from being a great wheel, when compared to other true force feedback wheels, such as the the Logitech Driving Force Pro, which works on PS2 and PC, cost less, and destroys the Fanatec wheel in every way performance wise.