I love the speed of the game, the pace. I love how water doesn't drown you. The weapons are dope to use. Level design and monster design are great. I like the chunky gore animation. Took me right back to my days playing Quake 2 as a way-too-young kid. It's a really good idea to make the monsters scream out when they see you since it signals to you that it's fight time.
What I wish:
1) Switching between melee and thrown katana mode was instant. I like to pop over to give the enemy a slash in between gunfire, but if it's stuck in ranged mode then it doesn't work so well. Maybe have mouse 1 melee katana and mouse 2 immediately throw katana. It would make the katana fighting feel as smooth as the movement.
2) Pistols always loaded when you switch to them. Similar to 1, it doesn't feel smooth to switch to pistols in a desperate situation and find they need to be reloaded while you get beat on by a demon. Maybe that would make it so you could kinda cheat the reload by switching to another weapon then back to the pistols, but I don't think most people would do that even if it was faster because it would feel weird to them.
3) This isn't important as 1 or 2, but I would like to see more personality from the monsters. I loved in Quake 2 how the monsters had little personalities. The big guys moved with swagger, the little guys cowered, etc. I feel it with the yellow gunners (they seem more sneaky than the melee guys) so I'd love to see more of that with future enemies.