The Mustang in IL-2 always gave me the impression of a half finished job..
The ground handling (and the non steering tailwheel in particular) is too stiff, the landing gear doors should come down as soon as the engine go off..
As for the handling, the thing that is mostly wrong is the roll rate: the Mustang has a surprising fast roll rate from low altitude.
I have to admit I haven't played with it for some time (I'm mostly a 109 guy), so I don't remember how it performs in terms of stall characteristics (remember that the laminar flow wing meant no buffeting before stall), but I have just this memory of a quite chunky ride..

SJ