Depends.
People say the FM's different, but frankly the only thing really different is the general depiction of torque characteristics. IL2 planes are pretty docile when it comes to torque, whereas AH2 can be said 'vicious' when compared to IL2.
I find AH2 to be more believeable in that aspect, but the rest of the flight characteristics are comparable. What I can do in a 109 in IL2, I can do in AH and vice versa.
There are some subtle differences in the feel - Both AH2 and IL2 planes handle smoothly, but under harsh maneuvers at extreme low speed maneuvering IL2 planes tend to 'mush' a bit more, whereas AH2 planes react in vicious stalls. In some cases AH2 seems more correct, in other IL2. Under some circumstances AH2 stall behavior seems better, in other IL2... and etc etc.
IL2 uses a bit more complicated general plane management, and some people treat it as if its Microsoft Flightsimulator, but in reality IL2 is nothing more than maybe 2~3 buttons more management than AH2. Basically both games are simplified as it is.
IL2 has botg its strengths and drawbacks in detailed immersion, and this doesn't apply only to the graphics. On the other hand AH2 has its strengths and drawbacks in its simplicty.
Without any prejudice against either I can say both are worthy simulation games, with slightly different approaches to some key issues concerning the simulation aspect.