SKJohn, I've been playing multiplayer in IL2 and IL2/FB since it came out, and have all the addons.
The graphics quality and attention to detail is very nice and immersive. The FM is probably one of the best for boxed games, but in all honesty I find Aces High more believable.
The take-off/landing is much more difficult in IL2/FB/AEP/Pacific Fighters, and that's one part I like better than AH.
However, all the planes feel somehow 'generic' when it comes to low speed handling and torque. In AH torque is a mighty factor - managing your plane to do a straight 90degrees vertical is always a challenge. Planes with high torque like the 109 keep want to slouch to one side.. and etc etc.. However, FB/AEP/PF feels very generic in this area.
Also, the use of flaps is something I don't like, and FB/AEP/PF is virtually a flap fest. Add in the little disappointments like manual RPM control exploits and etc.. and the MP experience is fairly ruined.
Unless one flies in organized scenarios with the online-war organization, the regular MP experience isn't bad, but AH beats it hands down.
Besides, AH2 is taking shape nicely, and while it's not state-of-the-art like FB/AEP/PF and etc, the graphical quality of AH is slowly making progress and I like it.
Both are excellent flight simulations, but I would favor AH over FB/AEP/PF.