Single player is fun enough but does get repetitive. The tutorial and seven missions deliver about 7 hours total gameplay and even in such a short stretch you come to recognise a few basic structures that keep cropping up over and over again. There are some furious fire fights though and even on normal I found the missions challenging enough to complete.
Multi-player shows a lot more potential. You select one of four classes (assault rife, sniper, RPG or submachinegun) and one of four specialisations that will allow you to unlock things like a portable mortar cannon or an EMP beacon which disable vehicles. Vehicles play a big role in the game and there are many including a wide range of wheeled, tracked and flying vehicles. Throw in the fact that one of the specialisations allows you to control drones mini-tanks or mini-helicopters and you can see that there are many many ways to play.
Personally I think the aircraft are overpowered being both hard to hit and packing a heavy punch but that could be just sour grapes seeing as I cant fly one for nuts. Land vehicles on the other hand are if anything underpowered with tanks even being easy pickings for any aircraft or a footsoldier with an rpg.
On a typical night there are about 50 servers on line with about 500 people playing so it is usually easy enough to get into a game. Sadly the most popular maps are the ones with a heavy emphasis on aircraft which sucks a bit if like me you can't fly. Foot soldiers are still needed however because the real objective of the game is to capture control points and that is hard to do in a jet.
All in all I would heartily recommend the game at its current bargain basement price from Steam but be aware that a number of people have experienced difficulties getting the game to run. While the game runs well for me I did have an issue that prevented me from joining Punkbuster enabled servers.
Two things to note if you do get the game: Firstly this game hates X-Fire. Disabling X-fire gave me a noticeable increase in smoothness and frame-rate.
Secondly once you have finished the main campaign be sure to check out two bonus missions that can be accessed from the options menu via the bonus codes "sp-village" and "sp-street" respectively. In my opinion these are the two toughest but also the most enjoyable missions in the game.