From both a production standpoint and a gameplay standpoint.
Production wise it's literally the same levels recycled over and over for the majority of the progression. All they add is some voice acting that advances a story with no weight, with the only different thing being where you spawn and which path you take through the level.
The levels and gameplay feels more cheap. Every time you complete an objective a horde of enemies will magically teleport in. Not only do they come equipped with homing fuel rods, if you try to back up to regroup these relentless dogs will chase you to the end of the earth. And they see through walls so don't bother hiding. Not like hiding will get you through the level anyway. God forbid you take a breath before more of them show up.
I literally just fought through 4 waves of 3 knights, all spawning on top of the exact same spot, the exact moment I kill the previous wave. I don't mind deaths if I mess up and get flanked, but having them all spawn right on top of you? Infuriating. /rant
But the new updates are pretty fun, so far. Wonder how long that'll last before dmr users start hating.