Call of Duty has been a long running franchise based around World War II, with the exception of the Modern Warfare duo which is set in present time. Originally starting on the PC it didn't take long before it expanded to the console and hand held platforms and from there it has grown exponentially.
Modern Warfare, was and still is one of the most played online first person shooters, personally it is the game that I compare all other online multiplayer's too, and since its release in 2007 has been unparalleled.
MW 2 for all its upsides is still largely an online multiplayer game, only giving the player around 7hrs of single player campaign (the 7hrs are action packed though) picking up where the first MW left off just 5 years in the future. Although a lot of people will be put off by the short single player campaign, keep in mind that this game is designed moreso to be a multiplayer, unlike the previous COD games that have been largely single player.
Some of the most outstanding features of this title aside from the gameplay are the graphics and audio. The visual appearance of this game is impressive as always, with some great textures as well as environmental graphics for your surroundings, the layout and feel of the levels are well designed, giving the player a lot of free range to make their own paths to their objectives helping cater to people who like different styles of gameplay i.e. stealth, close combat, sniping etc.