Is it worth it? How much time do you spend sim racing? I race every day for at least an hour...some days as much as 4-6 hours, so for me, it was well worth it. I still have the g25 and CSR wheels that my son and I use with our console gaming systems on occasions, but for PC gaming...it takes the simulation to a whole new level because of the strong FFB, great buttons/sticks/knobs, and general feel of the system in a racing seat.
The Thrustmaster t500 rs is certainly a comparable wheel system, and many people feel that the Fanatec is at least on par or perhaps even better because of the controls. I've had limited experiences with the t500, but universally users tend to like the Fanatec pedals better (although you can use the Fanatec pedals with a t500 as well as a Thrustmaster shifter with a Fanatec wheel). I'd say that if you are on a tight budget (can't afford a cockpit/racing seat), the t500 might be a better starting point if strong FFB is what you are after.