I have enjoyed WWIIOL in the past, but it is a much different game than AH. AH is a much better flight environment. Part of the reason AH is much better for flying than WWIIOL is the visibility -- not just the murky skies in WWIIOL but the whole view system in WWIIOL, which sucks. The visibility is always poor, you can't see behind you, but worst of all is that your icon indication of an enemy goes away once you shift you view. So, once you do aquire a target, if you shift your view to keep him in sight, you lose the icon on him, which makes it extremely hard to track anyone through the murk.
Another big difference is that a big furball in WWIIOL seems to involve about 5 planes, and there are times when you can fly around for an hour and end up finding maybe one enemy to fight.
At least that's how it was -- it's probably been about 6-12 months since I last played it.
It does have some interesting features. The planes do seem to have interesting damage models. The scenery looks good. Overall, though, AH is just in a totally different (and much better) league for flying.