Look, tomorrow is the last day the SR2 shit is on sale.
I'm not blowing smoke out my ass when I say that if you do not acquire all three add-ons (Corporate Warfare, Ultor Exposed, and the free Unkut Pack), we will not be able to play it any more.
Yes, in theory you could play the campaign in single-player yadda yadda yadda, but remember this: there are achievements specifically for beating the campaign and whatnot in co-op that I want. I can't get them without a co-op bro.
And also, both paid add-ons have fun missions(!), plus exclusive co-op minigames.
And trust me, the last mission of Corporate Warfare is probably the best videogames moment ever.
oh and all of your favourite characters get new lines
if you favourite characters happen to be the main character, pierce, and dex
plus there are some new characters
if you're into that