Online, MP only shooter which does a variety of things very well.
However, for the rest of you dying to eat up some bandwidth, give Warhawk a shot. There are only a handful of maps which scale to match the amount of players (up to 32 on one server), but with so many ways to wreak havok on your enemies you may never grow tired of Warhawk.
Your initial foray into the world of Warhawk will most likely be a very frusrating one. The instruction booklet is painfully uninformative and vague, such that you may not figure out how to reload your weapons for several days (anyone struggling with this can send me a PM). This means the learning curve is more akin to a brick wall than a hill. You will get pwned... a lot.
Your character will spawn somewhere on the field of battle armed with two grenades and a pistol. You can grab various weapons pickups scattered across the terrain, such as assault rifles, RPGs, and infrared binoculars with which you can call in devastating airstrikes. On foot, Warhawk plays out like a third person shooter, and actually does so very well. A properly equipped soldier can hold his own against almost anything he will encounter during his foray into DM, TDM, CTF, or Zones combat.
You want to try something new? Feel free to hop into flak cannon or SAM emplacements, jeeps, tanks, or the ever-popular warhawk aircrafts themselves. However you decide to enter the fray, teamwork is key; there is always strength in numbers. This tenet is as valuable to success as individual skill, so do yourself a favor and make sure you have a Bluetooth headset you actually intend to use.
The more you play, you will be rewarded with medals and ribbons which, aside from looking badass, will open up more options for character/warhawk customization, which basically lets others know how good you are on sight.
Software updates have been released in a surprisingly steady stream since Warhawk's release. There are already two add-ons, several free updates, and a patch (Q3 2008) which includes Trophy support along with various gameplay additions.
You are given the option to control your vehicles using the sixaxis's tilt capabilities, but this is obviously difficult to do. It is much easier to control your aircraft with analog sticks, but those who stick with the extreme learning curve involved in picking up the tilt action will probably be rewarded in the long run with a greater level of control.
With so many ways to contribute to your/your team's success, your favored method of mayhem may change with each passing hour. This is Warhawk's main strength, and is what will keep you playing for months and months to come.