Battlefield 2 follows this formula exactly and, as a consequence, the game is a chaotic, vibrant affair. The experience can change instantly from lonely flag defense duty to a desperate dash for cover from artillery or an air strike and then fighting off hordes of infantry or armor while spamming chat for help.
Despite the abundance of vehicles on most maps, infantry is quite potent. Typically, the more heavily armored a vehicle, the slower it is. Top gunners make tanks and APCs much more difficult to sneak up on, but the machine gunner is obviously vulnerable to small arms fire. Fortunately, modern tanks are equipped with gun shields that at least protect him frontally, making the position not quite as suicidal as it was in Battlefield 1942. The terrain rolls a lot and provides much cover - both against guns, like rock formations, ruins, and trees - and just plain grass and bushes to hide in. A tanker's life isn't easy.
As always, the damage system is simplified but generally sound. Vehicles take a lot of damage from the rear, less from the side and less still from the front. Only powerful weapons like missiles, bombs, rockets or tank guns can destroy tanks reliably, though grenades still do token damage. Three infantry classes specialize in attacking ground vehicles. Obviously there is the anti-tank class with his guided missiles, but the engineer and special ops have their tools as well. Engineers lay mines on the ground, which are extremely effective at denying routes to enemy tanks. They're much harder to spot than in BF1942. Special Ops have satchel charges which can be thrown from close range at the tank and will then stick to it. Two charges are enough to blow your enemy to bits.
Classes have duties other than combat as well. Satchels from the Special Operators can be used to destroy UAV launchers, radar sets and even that damnable artillery. Obviously the engineer, in addition to repairing vehicles, can be tasked with repairing these items as well. Medics, quite naturally, spend their time healing their teammates and distributing health packs. The Support class re-arms his allies. It should be noted that when these classes board a ground vehicle, they create their heal/repair/resupply auras automatically.
Above all the mere classes is the elected Commander. Possibly the most important position in the game, it's virtually a full-time job with 32 or more players, leaving little time to actual combat. Commanders deploy UAVs, drop artillery, scan the battlefield and drop supply crates (which heal, repair, and re-arm at a pitifully slow rate). Most of all, if the players are co-operative and form squads and fight as squads, the commander can give them objectives that they can see on the map and the screen. In the hands of a good leader with a willing team, this means the difference between victory and defeat.
Best of all, it actually works. These features are all optional but attractive. They're not so weird as to scare players away and their effectiveness, especially with the built-in voice comms system, is so great that people are willing to try squads. Depending on the server and your team this may or may not be difficult to accomplish, but at the very least clans are willing to go into one squad together. The streamlined and thorough implementation is to be admired.