Buy it, if you like this type of game. Who matters what other say, if you have your own opinion? I read a lot good reputation about Black Ops 3 and I am playing it now (pre ordered). Its nice to play, nothing special about it. But on the other side, the last Call of Duty I played was Modern Warfare 2 years ago. So its just time to play an actual one on single mode.
I read somewhere in German sites that the game is poorly optimized and you need really high power to run this game optimally. I have same graphics card and a cpu with similar power + its hyper threading. So when I get acceptable playing rates, then you should too. I first tried to play the game with mouse and keyboard, like I do on Counter Strike. But after 1 hour I switched to 360 gamepad and it is much much better now.
I buyed the game for the single player mode and its fun to play. If you like such games and want to play it, then I can recommend it.
Alternate recommendation. What type of game are you looking for? Just don't know what to play? Must it be a new and actual title and would you play games which are not AAA. I mean, would you play smaller games, like those of indie studios? Are you looking for online games only? Or maybe even strategy games? Well, here are some recommendations from me:
(Relatively) Actual big productions:
Metal Gear Solid V: The Phantom Pain
The Witcher 3
GTA V
Multiplayer games, some of them for offline with friends on couch, some are online:
Rocket League
TowerFall
Duck Game
Not new, but still good:
Batman - Arkham City
Outlast
XCOM: Enemy Unknown
Games I didn't play:
ARK: Survival Evolved
Middle-earth: Shadow of Mordor
A game from a friend (indie production):
The Curious Expedition