The best First Person Shooter

[FlawlessHappiness]

Payday 2 was just released a few days ago. Unfortunately I can't tell you much about it, because I don't own it (yet). A friend of mine really likes it and described it as "challenging,motivating,fun", and I must say ,judging from the screenshots I saw, it really looks pretty cool.
Maybe this game is an option for you?

Maybe. I've been considering it too.
The concept of having to rob a bank is great, and a new kind of FPS.
I just got a little disappointed by a video is saw of Payday 1, because it made it look like you must have 3 other friends playing with you...
Is it so? Because I'm guessing that's why you're able to buy a 4-pack.
Is it playable without friends?