Graphically, it's better than AH. Terrain is somewhere between IL2 and AH.
Since my computer at home can't display all the textures in WB3, I am quite content with the lower graphical detail in AH.
Aircraft look only slightly better than in AH.
There are some bugs-shadows of parts of the airplane that have been shot up are still visible , control surfaces that are still there sometimes appear to have been removed.
Flight model is quite similar, except that roll is much more sluggish. I don't know which of the two sims simulates it more realistically.
Damage model-sucks beyond belief. When the tail is completely removed, the plane continues on the same trajectory as it was.
When the vertical tail is destroyed, aircraft is still controllable in turns.
I have only tried the sim offline, therefore that's all I have to say for now.