I jumped in because of the new flight model. From the manual:
Oh, and there‘s one more flight related thing we should mention. There is a completely new flight model that is we believe unprecedented in PC game flight simulators. This one is based on a full physics model for air and ground operations. This is complemented by an implementation of the F-16 flight control system that is a faithful model of the actual system used in current inventory jets. Combined, these models create a completely different feel from any prior version of the F-16 in the Falcon franchise (or any other equivalent for that matter).
After a couple of hours flying, the flight model certainly feels different. That sensation of "flying on rails" is definitively not there. Boy, there will be a lot of re-learning now.
The list of newly added/modified items appears to be hefty.
One of them is fully supported TrackIR 6DoF. Outstanding!
All you need is the original CD for Falcon 4.0 and a download from this link.