absolutely bullshit hard. ideally you would start with easier room and then crank up the difficulty later on
sometimes enemies get stuck on corners of the geometry of the map (pic) or on doors and i can shoot at them safely without being overram
sometimes enemies spawn right next to you and you don't really have a way to know until you have learned the spawn locations via trial and error.
i like the shotgun the most. enemies are so bulky and so fast and so numerous that trying to kill any one of them with the chainsaw is suicide. melee weapons should be much more powerful to compensate for their lack of range.