After playing offline practice two times, once as commander and once as HWG, and getting a loose grasp one the game, I played one online game. As the team didn't have a medic, I chose that for my class.
People kept senselessly pushing forward even though teammates were injured. When I dropped health packs, people often simply ignored it. Two people decided that going solo was the way to go and got killed. Then people started to become "infected". Not having faced this situation before, much less as medic, the game showing me a "left click" notification over the respective team mate told me that I should left click on him, which did nothing, even after changing weapons back and forth (don't shoot squad members lol!), then told to me press "Q", which did likewise did nothing, until eventually I just thought "screw it" and threw a kit on the ground, which did the trick. After he recovered, he stormed forward and was killed, promptly followed by me getting killed.
Game over.
Bottom line after the first online game:
Very limited resources and tolerance for mistakes plus a strong reliance on teamwork is bad for pub gaming, especially if you have little experience.
Maybe in coop with steam colleagues of whom you know they aren't Leeroy Jenkins...