Firstly, thank you for playing!
The stunlocking thing I think is actually just a weird stroke of luck (or unluck) since each enemy has a set chance to play their pain animation. The idea is that the fist would work as a means of stunning enemies that get too close - buying you time to use another weapon. But since everything does more damage while firing faster (except the Damocles) it ends up being kind of redundant once you get the rifle or shotgun.
The decorations are sort of a work in progress. I definitely agree there are too many areas with too little going on.
The regenerating health thing was actually a last-minute decision to make sure that people would be able to finish the demo. I agree that the Sal Guardsmen (the staff/spear guys) aren't threatening enough - but I also had to assume that there were at least some people who aren't good at/familiar with shooters playing the demo. Basically, I had to choose between accidentally making it too easy or too hard. Once I have health pack/healing terminal sprites it'll be removed.
The difficulty thing was my bad - the UI elements for it were present in the demo without it being properly implemented. The latest non-public build of the game has it working now, and enemies hit MUCH harder. It's still an open question as to whether or not I want the difficulty to affect enemy movement speed, though.
Oh, and for the record - I was watching the stream while you were playing it and Project Nortubel. I don't think you were too mean. It's better that the criticisms come at a time when I'm still able to change/fix things. Even then, I moreso got the impression that you wanted to like the game but kept being pulled out of it because of gameplay that wasn't asking enough of you as the player.