It is the same game but with more new features and content..
This time, Call of Duty tries to bring back people who adored Call of Duty 4 but then keeping what made Modern Warfare 2, World at War and Black Ops great. It is pretty much like a combination of each. May so many may notice that this time the game pushes the gameplay a bit further. I'll briefly explain.
First the campaign mode which has featured in every COD title to date. Now with better cinematics and storyline, it continues from where Modern Warfare 2 left off and does explain the previous and current story very well indeed. The missions themselves felt very real life and some were just outstanding to play through although the game still had it's very linear paths with a few exceptions to open-out levels. Since this is last of the Modern Warfare series, the game does sadly conclude the storyline which a little upsetting to those hardcore fans who want Modern Warfare 4 to continue it again
The Special Ops mode is now divided into two categories; Survival and Mission. Survival is a survival mode, you have plenty of enemies to fight, equipment and weapons to purchase. The mode is good enough to keep players playing although it doesn't have enough replay value once you max out your level. If you uncertain with Survival then Mission part of the Spec Ops is then your thing. The mission has 16 different missions set in parts of the campaign levels, it isn't exactly the same like the campaign but it has it's own objectives and missions. There would be a mission to save someone or collect these samples on your way fighting through defences and such. The special ops itself (mission mode) is slightly better than the Modern Warfare 2 but it really does lack difficulty, depth and creativity. It can feel a bit boring other than less, because it recycles campaign maps and doesn't really bring that much action compared to the previous ops.
Multiplayer itself is improved, i cannot really review it in depth until i reach max level but so far the game is a lot better than previous, some new features like point streak and such, there are plently more reasons to play this game than the previous.
Call of Duty Modern Warfare 3 is an amazing game with a few problems aside. If you are avid COD player then get this but if your after a true sequel with massive upgrades, best to miss this one.