Here' s what you get:

Vampire (New Plane): Plamsa balls as a secondly weapons, decent machine gun, rather sluggish though

Hellhound (New Plane): It' s shotgun second weapon is like the Fury, overall it' s a very fast plane

Firebrand (New Plane): Tough, fireball, built like a tank, yet surprising nifty

Lost Plateau (New Level): Lovely Scenery, waterfalls, rivers, all under a night sky, large level, with a few underground passages too

Badlands (New Level): A large Axio style canyon level

Chicken Pox (New Mode): To gain points you must shoot down someone holding a chicken (there is one per 3 online players) or shoot someone down whilst you are holding a chicken

Gun Heist (New Mode): You have to aim to capture the 3 AA guns per level and hold them for 60 secs

The best part... it' s all free!