It's okay. It has nothing on the likes of Assetto Corsa though.
If you start your career with the Karts, then it's a lot of fun and seems very promising. However, when you move out of Karts (and SuperKarts) you start to realise how bad the handling/physics are, which is a shame.
Still, the atmosphere, AI, weather, graphics etc make it a lot of fun in certain cars, but others just ruin the experience.
I've tried it with both a G27 and a T500RS. FFB is horrendous without changing anything, but can be made bearable with changes, which aren't easy with how complicated PCars have made their FFB settings :/
Overall, it's NOT a sim like they're marketing. But it is fun as just a racing game.