I haven't played iRacing but I only hear good things.
I think any sim racer has to at least experience it for a while. The cheap 3 month deal for new members is a good way to go, because it takes quite a while to settle into the iRacing "my way or the highway" scheme of things.
And to understand the interface, which I still think is an abomination, especially for new members. I am in a minority though, probably on all iRacing-related matters.
There's no doubt to me that iRacing represents the state of the art for current sim racing. It's almost worth it just for testing on your own. But it also represents the most frustrating sim racing experience know to mankind at times. I gave up after 2+ years because I started to feel like I was on a treadmill, and an expensive one at that (compared to other sims, not the expensive real world hobbies often cited as a good comparison).
I'd start paying again in a flash if they added either AI (so I could race whenever I want, wherever I want, in whatever car I want) or the Nordschleife, but neither are going to happen in my lifetime.
I'm an old git though. Younger people will have a better chance of seeing this project turn into something more flexible and fun. Though if you can race at peak times (UK evening for Europe) and don't mind coughing up a decent chunk to buy access to a variety of races and less time sat around waiting, you'll probably find it plenty of fun, and more than flexible enough for you.
Try it, the worst thing that happens is you like it, and there are worse things to waste your wages on. I just decided that paying to be a permanent backmarker in underpopulated, off-peak racing wasn't worth it. No doubt if I was a better driver I'd have found more satisfaction though, so that's why I always say everyone should try iRacing. For some people it will definitely be sim heaven.
Since giving up iRacing I've revisited all my old titles, but I have to say that nothing, so far, can lure me away from GT5 (not even NKPro). I've done more laps of the Nordschliefe in the last month than I've done in the past ten years, and in the right car is is an absolutely amazing experience, matching any sim-satisfaction I've ever found on the PC.
If only the same could be said for the rest of GT5. Whoever designed the overall gameplay needs their head examining. And the AI is slower than evolution. In a practice race with my rumbling beast of an upgraded (999HP!) Dodge Viper this morning I had to give them a 3 minute head start to make life interesting.
I guess now I know how the people beating me on iRacing felt.
Andrew McP