-The animations are either extremely fast compared to the rest (like shotgun), or actually moving, but slow (revolver) or barely moving and slow (pistol, assault rifle...) and many more troubles with that. It just feels like playing impaired slow-mo man. The only one that feels kind of alright is the plasma pistol, if not for being static while firing.
-The gunshot effects look like they're flying out of your arm.
-I'd speed up a little the spas pumping sound, as for now it just doesn't fit the animation (or make it longer, as gee whiz, on contrary to all other weapons, this is like you're shooting this gun after six espressos!)
-The sawed off firing sounds are getting cut off while reloading.
-The fire weapons reloading is extremely slooooow. (I can tell it's probably for balance reasons, but I'd chug in some extra frames there so it doesn't feel so choppy.)
-I swear I've seen this projectile in the alternate grenade somewhere before, heh.
-I'd align the casing drop in the revolver more to the right, so it looks like they're dropping from the cylinder.
-It probably was intentional, but it looks quite weird when the freezing plasma falls down after hitting the wall.
-This mod needs more particles, whizzles, kaplooeys, effects and whatnot! (Just a personal feeling.)
-The flamer pickup is sooooo tiiiiny - it's actually smaller than a pistol... and that gun is bigger than a pistol, I believe.
-I know that this selection speed is a doom standard, but I'd seriously speed it up - I just can't live without fast weapon switching these days, but it's your choice here, I guess. Just a little suggestion!
-I'm not sure what he's doing with the assault rifle when reload is done, but that sound cracks me up hard.

-I'd actually work on the pyro gun to make it work a bit different; I've seen it in so many shuffle mods that it makes me cringe when I see it.
-The sword, using up ammo while swinging into nothingness is a huge dissapointment, even if it actually kill stuff pretty nicely; I'd make it use it up ammo only when the hit connects. It also just feels meh; could have a use from adding more knockback or particles for the oomph-factor (also, I can see it turning into a knife for a one frame when swinging). Otherwise, its idle animation in pickup is waaay too fast, it just looks weird. And it could be placed a little higher, as it clips into the floor while bobbing.
-I'd condense the weapon slot placement to doom standard, or at least move the sword to slot 1 as well - I don't like moving my hand all over the keyboard to a melee weapon set at slot 0!