I have the old RealFlight Deluxe as well and I can also fly the Mustang easier than almost every other plane. I think the physics are quite accurate on this sim with one major exception. It doesn't simulate stalls very well at all. You wouldn't want to be landing the real thing as slow as the sim allows you to land the Mustang without incident.
The people above who soloed on 1st, 3rd, or 10th flight are not typical of most beginners. Most beginners without a simulator would take an entire season of flying. These guys did it in their first or second time out to the field and that's pretty impressive. My son is 5 and will learn on this sim before I hand over the controls to one of my planes. I think Realflight Deluxe may be the best investment I've ever made in flying.