The attraction for Gran Turismo and Forza fans is often the wide variety of cars and the tinkering with upgrades to progress in levels.
iRacing is quite different. You can't really paint the cars. You can't buy/sell them. You can't add a new engine or new tires, transmission etc. You don't race the AI. And instead of 600 cars, you have maybe 20.
When you think about it iRacing is a completely different experience. It's for the person who loves to race and compete. There are a bunch of Gran Turismo and Forza fans on their (I'm one), but we're there because of the desire to compete against real people.
iRacing will never be the sim for everyone, but if you love to compete it is now and likely for the foreseeable future will have the largest collection of the World's fastest sim drivers competing together.
The World Driver Championships will easily be the most challenging league title to win in sim racing. It pit the top 50 iRacing drivers together for a grueling 42 week season. Each week a different track and only the top 32 of 50 will get a starting spot on the grid.
It will be broadcast, but we haven't heard where/how yet. It might be on YouTube or on the iRacing website.
They just released this video today.
iRacing Explained by Leigh Diffey from Speed. It would cool if it was broadcast on Speed, but that seems too expensive, but who knows.
http://www.youtube.com/watch?v=IXy3PrXBV-o