Battlefield 3 will include both a singleplayer & co-op campaign and multiplayer modes.
Its multiplayer will most likely feature similar gameplay to the classic Battlefield 2. It was announced that jets will make their return as usable vehicles, that prone will become an available stance and that the PC version will be able to support 64 players in a same multiplayer match. The PlayStation 3 and Xbox 360 versions will be able to support up to 24 players in a multiplayer match. As seen in the Battlefield 3 gameplay trailer, it is confirmed that the player can now drag fallen soldiers and heal them from cover. However, it has also been confirmed that this gameplay feature will not carry over into the multiplayer aspects of the game. It will use a completely new engine, named Frostbite 2, which will be the successor to the Frostbite Engine used in the Bad Company series.
With the help of the Frostbite 2 engine, Destruction 3.0 will be introduced into the game. An improvement over Bad Company 2's Destruction 2.0, Destruction 3.0 allows for a much larger range of destructible objects alongside buildings and more realistic destruction. For example, when the player fires their AT4 on the hotel in the Fault Line Series Episode II: Good Effect On Target trailer, they can see the entire façade of the building being completely ripped apart. In the earthquake prone city of Sulaymaniyah, players will experience tremors and earthquakes that will display the capabilities of Destruction 3.0.
Audio is another focus for the game. There will be audio cues that, for example, will let the player know if a tank is moving towards or away from them, or if it is having trouble climbing a slope. The developers have recorded real life sounds of vehicles and weapons from a military training exercise; their goal being to create "cleaner and brighter audio." Voice acting will also be extremely varied. As stated by Thomas Danko, voice over producer at DICE: "No FPS ever had this large amount of VO variations for Multi Play, not even close. Over 300 for the "Man down" event alone."
Several sources confirm that console versions of the game will get smaller multiplayer maps than the PC version, though there will be little to no change in the graphics of the different versions.
Lead weapon designer for Battlefield 3 Alan Kertz stated in an EA PWNED interview (see video section):
"We're going for a really authentic feel in Battlefield 3. So the big thing that we're looking at is what guns are actually being used by armies, and obviously we have the Marines in Battlefield, so first thing we did is go in and look for the Marine weapons, but we also want that little bit extra special, because fun is still something really important in Battlefield. So, we went ahead and looked at other forces and said: "What sticks out? What looks cool? What is unique? What fills a role that we don't have?" And we went and we picked those guns and brought those into Battlefield, as well."
Source:
Battlefield Wiki