Hi Aur! I just played to Coop and everything seems to work fine.
The only problem I had was when one of the players got stuck when it was hit by a rocket. I couldn't move until a enemy hit me again, but the other character was able to play. I can't post any screenshot because it seems like it's not supported by Steam.
And as a suggestion, I would like if I could continue playing alone once one of the two players die; and if it were possible, have a health indicator for each player.