Please post impressions on Air Mail as soon as you can. I'm still on the fence on that one.
There are some performance issues on iPad2 regardless of settings (you can just enable/disable fog and bloom).
The controls aren't as good as Sky Gamblers AS, both touch and tilt are more simple and basic (left to turn left, not left to roll and then pitch up to sharp turn). There's only an advanced touch mode that's weird to me, and yet is the only mode that allows more complex maneuvers as there is no advanced tilt mode (yet at least, advanced touch was unlocked past the first set of levels).
There's a normal third person and a first person camera with no cockpit and then a couple other useless camera modes you can't really play in (maybe top down helps you line up some package drops, I dunno), one top down, one cinematic.
The game seems to have some charm, the levels aren't just generic terrain and box buildings as in SGAS but more structured, they look kinda like a platform game's levels, that's probably why it performs visibly worse even though it's not as shiny (no motion blur etc). It's very kid friendly and simplistic in presentation so don't imagine something like Crimson Skies based on the setting either.
You either do missions in order which so far are going through rings and taking and delivering packages (by flying just over/by stuff, you don't have to time a drop or anything) or go in an explore mode that lets you "find" stuff similar to the Wii Sports Resort airplane mini game in whatever areas you have unlocked. Basically just flying through floating objects.
Edit: ok some missions have different presented objectives, scare pigeons off places, catch and drop fish, spray stuff over crops to make them giant, whatever, but you do the same action in all of them, you just fly close to stuff and through rings, some times in sequence. I guess each area may have its own objective presentation like that.
There's a time/point trial mode too, where you do some of the same things.
It's probably a pretty limited in scope game going by what I've seen so far so you may wanna wait for a deal. SGAS impresed me a lot more at first plays, before the shortage of content and variety became apparent, this is just like, neat, but I could have waited for the inevitable price drops. Hopefully they'll add more SGAS style control options in an update at least.