There are a lot of quick-time events in the game, and when one happens, it only happens to one player, so the other just has to sit there, not interacting with the game, and can only watch.

While the co-op mercenaries mode is fantastic, Resident Evil 6's campaign is pretty boring. One level, for instance, basically has you walk through a room and back. Another has you walking through some buildings and down a road, stopping every few feet for another pointless cutscene.