Don't buy this if you are expecting a "Call Of Duty" experience. This game has failed on so many levels to bring a call of duty feeling.
The famous "Run and gun" play-style that is so widely attributed to Call Of Duty is simply not feasible in this game. Instead, players are encouraged and rewarded for sitting still in the same room for as long as possible, with claymores that can be infinitely replenished over a short period of time.
This game has potentially the worst spawns I have ever experienced. One reason for this being that since the maps are so large, you often spawn all the way at the back. Meaning you can end up spending a huge amount of your game time literally running to find people. The game also seems to arbitrarily spawn players in ridiculous places, often being right in front, or behind an opponent.
Tying in with spawns is the map design. Since the maps have no real system (for example, the more typical 3 lane maps), you can easily find yourself being shot from 3+ locations at any given moment or place on the map; further encouraging people to camp since there is so much risk in moving position, with the potential to be seen from an abundance of lines of sight.
There are still some positives, such as the gun design. The guns feel amazing and all seem to have their place. However, at this point in time, there is desperate need for nerfs and buffs, since the entire game is dominated by a few specific guns, mainly the M4 and 725 shotgun.
This game has a lot of potential and can still be made great, but Infinity Ward need to address the issues present.
If you're a very casual player, you can still enjoy the game.