I tried iRacing around January this year and I can say I was bitterly unimpressed with it.
Until around 2 weeks ago I still had the same verdict about it, but then I hired another month and with a completely different state of mind from the first time round, then drove until I am where I am now, Class C road course 3.55. Now I thoroughly enjoy the simulator and have purchased 2 tracks, the Ford Mustang and FG01 V8 supercar. My opinion has completely changed about the sim because of the state of mind I went into the simulator with the second time round.
The moral of the story is, You can not drive iRacing in the same manor you would drive LFS. You need to be cautious, you need to be concentrating 100% every lap and if you let go of that concentration you might as well withdraw from the race. That is what I love about iRacing, it is a real simulator. Forget the cowboy overtakes, forget the flat out through yellow flags, forget not concentrating on anything but your own line, because if you even think of doing anything I have mentioned you are doomed from the green light.
That is my take on iRacing.