What this new Battlefield Onslaught mode does is force players to use teamwork, and that’s a good thing. Instead of everybody going Rambo and taking off by themselves across the map, you have to stick together. You can respawn behind a teammate, just like in the regular game, but the catch here is that the game ends when all four of you are dead at once. This means that if you are the last man standing, you need to find cover and wait for backup to arrive.
I see it as a pro more than a con that Onslaught makes players use teamwork, because if you learn to work with other players in this mode, then you’ll do much better in the Multiplayer modes. One really good player can do well by themselves, but two mediocre players who back each other up can dominate every mission with just a little bit of teamwork.