Call of Duty 4 is without a doubt one of the best shooters to date. The single player campaign is short and lacking co op but it makes up for it in challenge and sheer replay value will probably last you 12-20 hours. Playing through on normal might seem like a decent challenge but once you take a step into hardened and veteran it takes the game in a whole different direction. Dying in 2-4 hits makes this game an insane challenge to get all the gamer points. Now the multi-player on the other hand is possibly the best Xbox Live has to offer. The amount of customization and possible class structures is insane. It rewards players for being good and doesn't deny worse players form the same equipment. Even with all the 50+ ranked guys starting with basic weapons will not hinder your chances of winning. Now to the negatives. While the single player has a decent length and story some might be turned off at playing through on a higher difficulty due to challenge and no co op which would have been nice. Multi-player is outstanding but due to spawn camping and the annoying people on Xbox Live it might make you stray from playing it very long. Bottom line if you even have the slightest interest in a good shooter or war game buy this.