Just got it up and running now. I must say first, I'm suprised how negative some people are being about the overall sim, especially the interface. I was expecting it to be a complete mess, so I was actually quite suprised at how straight forward it was to set up with a bit of patience. It does have it's problems, but I'll go on to them later.
Anyway, in terms of the driving, it's fantastic. Definately up there with the best in terms of feel and physics. I can tell exactly what the car is doing, and slides etc are all catchable.
I'm, guessing the F1600 has an open differential? That would explain the oversteer off the throttle, especially at low speeds, so I see nothing wrong there at all. The force feedback feels spot on too.
Other than the other problems others have pointed out, I have my own niggles now. Firstly, the sound. The samples they have used are terrible quality recordings, and the individual samples aren't blended well at all. I'll be having a proper look some time in the future to see if I can make any improvements to them. Still, they are functional (just).
One major problem I'm having, and more so with this than any other sim, is tearing. Now either I turn on v-sync, and get quite major lag which massively impacts the connection with the car; or I limit the framerate. In other sims I limit to the fps to just under 60, so that I get little to no input lag, and very little tearing. However in NKP the tearing is horrific. Any help or suggestions? Cheers.