When I got it, it was super stiff, but more so than was comfortable to use. I looked online and it's expected, but it gets softer after a while. I can confirm that just 2 weeks after starting to use the performance kit, it's already gotten a bit softer.
One thing I'll note though, I don't have a cockpit, I screw my pedals onto a wooden block which I've connected to my desk to keep them from moving. I also have a chair which has wheels. The amount of force necessary to drive properly is a bit more than what my home-made setup can handle, which is a bit frustrating.
So basically, the performance kit does its job perfectly, but I'd recommend either a really sturdy home-made setup, or a cockpit for this. The stiffness does get a bit softer with use over time and it seems to be getting to a more comfortable state.
My only wish is that, although a niche issue, I'd prefer it being easier/quicker to remove and put back. Sometimes I want to play more chill driving games and don't want to be using so much force - like American Truck simulator or driving different types of road cars. When it comes to hotlapping or racing though, there is no way I'd drive without the performance kit anymore.