It truth it's the character swapping that makes the game such a confusing mess, at least initially. The next problem centres on the game's revival system. As long as one character is alive you are too, so it's essential you keep them on their feet.
Complete death wouldn't have been a huge problem had it not been for the game's dreadful checkpoint system. It forces you to play in a very negative fashion, which hurts the game as it's at its best when the whole team is unleashing hell on the hordes of oncoming enemies.
This is all a huge shame as Jericho had tonnes of potential.