Battlefield 1943 is a great downloadable game, that will give you plenty of bang for your buck.
You have 3 character classes with preset weapons. You have a scout (sniper), Infantry (machine gunner and anti-tank), and Riflemen (to take out infantry). The classes are well balance and each plays an important role. There are also several vehicles to choose from, jeeps, cars, tanks, and airlplanes. Vehicles make a big diference in how you play, because without them you get killed very easily, and it takes a long time to travel without them.
Perhaps the greatest thing about Battlefield 1943 is the destructible environments, almost everything is destructible. this can be used to expose enemies or create lookout places.
There are several maps that are all very different. They add some variety to the game. Also, squads are very effective to be able to take control of the battle. You can spawn on your squad, allowing you to have backup when trying to take a command post.
The only drawbacks to Battlefield 1943 is that the headset support doesn't function properly and there's only one gameplay mode. Your mic will cut out randomly, and headsets rarely work when you are in a squad.
All-in-all, Battlefield 1943 is a great game that is worth of a purchase.