Never played Wings of Prey so I wouldn't know. Also I wouldn't call it an MMO, I think there's something like 32 players in a game. But there are some strange options you can see for leveling up "Ground" and "Naval" stuff, which makes me think that they intend (longterm) to allow players to operate a lot more roles on the battlefield, which implies a much larger server size.
One of the coolest things about this game (imo), is that the AI aim is in this perfect sweetspot. Ground AA will seriously mess you up, and if you're in a larger plane with tail gunners you can either change seats to take over for the gunners, or let them do the shooting. Going up against a monster like a B17 is a nightmare with all those AI gunners raining death on fighters.
Bombing in general is also incredibly gratifying. You're slowly moving this absolute behemoth of a ship through hostile fighters and AA just watching your little ground target reticle waiting for it to show that you are in place to fire.