Warhawk has been given the next-gen treatment and is now an amazing MMO game with a very reasonable price tag.
Firstly, the range of vehicles and weaponry is excellent - particularly with the new Operation Omega Dawn introducing the Dropship (a formidable foe even agains a mighty warhawk!). I cannot tell you which I enjoy using the most as all have equal pros and cons.
Next, although there are only 6 maps which are played in rotation (5 without te expansion) this is enough as they can be played for a maximum of 60 minutes and you wouldn't believe it but in some games this is all too short!
Finally, i will say that for £20 this game is a real bargain and will provide you with hours of entertainment. Whenever I am bored I simply dive straight into a game on Warhawk. The only downside I can think of - it takes ages to rank up!