It definitely depends on what you're looking for as to whether it's worth the money or not. Definitely a bit pricey, but the content that comes with a subscription is enough to satisfy for a while. The one thing that keeps me coming back to it is the ability to have good quality races whenever I'm in the mood. I'm racing the Spec racer ford and the Skip Barber right now, each of which offers races every 2 hours but they alternate so if I were so inclined I could expect to have a good race nearly every hour of the day. I think that is what will keep me coming back to the game for a while.
I got a free month offer that came with the radical and silverstone, but I haven't been able to use either in an actual race yet. Besides that the only content I've purchased so far is the Skip Barber car, and I can compete in at least half of the events over the season with just the stock content, and would need to purchase a couple tracks if I wanted to do the whole season.
Sorry if that was a bit off topic. I'm looking forward to the Jetta TDI, it will be interesting to see how FWD handles in iRacing. The C6R and Lotus will be awesome as well, but it will be a while before I'll have my license up to compete in those.