The best way I can think of to explain FSX's improved flight dynamics... is that it's like they're buffered, and kinda "re-curved". Rolling into a turn for example; It's not like it's a less linear thing... it's like there's a proper parabola to it. Soft at first and then a bit more pronounced as all forces converge and then the "stop" (as in you hold a bank angle) doesn't just HAPPEN. It too is sort of buffered. You can really feel it when you enter ground-effect.. and really really feel it if you're cross-controlling a crosswind in ground effect... And where it's most noticeable is when the plane gives up and settles onto the runway. It's much less of a jerky, final touchdown... it's very realistic and rewards you for holding the plane off, just a bit longer (just like a real plane). That same, less jerky, "buffered" sense comes into play during turbulence too.
There was a similar improvement in the jump from FS2002 to FS9.. this is just that much better. I'm not naive enough to think that they redid the flight model algorithm, because stalls and spins are still "not right"... but they did add a line or two, to the formulas that affect how each vector is applied to the COG. Or who knows.. maybe they took a line or two out and made it all more efficient... or both
