I hate to say me and buddies contributed to that success, which I do not believe was deserved. It was a supremely derivative game that became a slog by the end. The whole thing was a cookie cutter experience, no really interesting missions, very little diversity and almost no interesting dynamic reaction/usage of factions and villians. You never felt you were actually fighting a cartel, so much as doing the same old Ubisoft checking the boxes/collection type thing. There was no dynamicism in the game. I think that's what ultimately bugged me about a lot of other Ubisoft games like assassin's Creed over the years too. But this was much more pronounced in those ways.
The land was really cool, but my God was none of the story even slightly worth playing.
At least it says one thing though. People definitely want Co-op games. Which I'm all for.