The world looks really great, but the general aviation (small propeller) planes do not feel very realistic in my opinion. I haven't spent much time dialing in my controls yet, and I have no idea what it takes to modify the physical models of the planes. To me it feels kind of like the planes have far too little inertia, they feel kind of "twitchy" and unstable. And, sometimes you put out full flaps when you know you have the airstrip made, and suddenly you find yourself near full throttle just to maintain airspeed and sinkrate when you should be able to glide the rest of the way in.
Hopefully when 3rd party planes become available they will get better.
Unfortunately, the term "flight model" is a mystery to many players and the actual "feel" of an airplane is hardly ever questioned. As long as the speeds are correct, most users are happy with it and tend to pay more attention to the realistic behavior of the autopilot heading knob and similarly "exciting" details. But a flight model is not only about the main performance specifications like speeds and climb rates, but about a detailled physical representation of the dynamics
Now try to find information about the flight model of any flight simulator. Often the developers only mention that it is a "physics based" flight model (no really? And the others are "philosophy based"?) or that "dynamic forces" are modelled - sounds cool, but means nothing. Even the simplest model considers dynamic forces.
Admittedly, the actual details of realistic flight dynamics are not easy to judge. The feeling that some aircraft feel "stiff" or "twitchy" compared to their real counterparts is one thing, but actually measuring and nailing down the error is much more difficult.
For me personally, the most important part of a flight simulator is the representation of detailed flight dynamics and the corresponding feeling to show the true character of the aircraft. I consider a complex flight model more important than just spending time adjusting the model's fitting parameters so that all speed values are hit exactly.
For big ships like commercial airliners, this does not play a big role. Even with a very simple flight model, they can easily be tuned to meet their specs and will behave quite realistically, simply because these big ships have such low manoeuvrability that complex dynamics simply would not make a big difference, at least within the normal operating envelope. But for small GA airplanes, these details will be much more pronounced, especially in aerobatics and post stall maneuvers, which often feel "stiff" or "scripted" due to a lack of detailed dynamics.
However this should be no surprise. Why should a developer spend a lot of time developing a good complex (and more resource-hungry) flight dynamics model when the vast majority of players would not even recocnize it? For most users, eye candy is still the number 1 criterion for the realism of a flight simulator.