There's no other way to say this: when you first play this game, you will hate it.

First, you will try out the situations (kind of like the story mode), probably die the first few times, but you will get the hang of it. You'll feel pretty good about your self and decide to hop into Casual PvP (the backbone of the game). You'll get rekted, you'll get rekted, and you'll get rekt.
Eventually, the person that kills you will taunt you saying something like "lol ez" and you'll want to throw your computer (I know I have). You probably won't play for a few days maybe even weeks and then one day, as your taking a shower or walking your dog you'll remember that guy and the stupid way he killed you (it might even involve a tea bag). Suddenly, you'll feel an urge to get better at the game, to beat him, to beat everyone.
You'll start playing terrorist hunt (PvE) and your aim will improve and so will your map knowledge. You'll watch a couple youtube videos explaining some tips and tricks and you'll build your self-esteem back up. The moment of truth will come as you hop back into PvP.
Your team will all be dead and it'll be match point. All your friends will be at the edge of their seats spectating you and everything you've worked for will coalesce. Before you know it, you'll have clutched the round and your whole team will be cheering you on. Your arms will be shaking and pure adrenaline will be coursing through your veins.

You'll lean back in your chair and gingerly type into chat, "lol ez"