I feel like after playing maybe half of hard mode is that ii's seriously flawed. The normal mode is fine, you can be very strategic with the routes and tactics you use, but hard mode relies too much on luck; at least for me when I play. I have to hope that the one guy misses with his shotgun, hope the guy doesn't see me with the gun, I feel like they could have done better with it.
I don't know if it's just me but imo I feel like there is too many enemies in small areas. This also adds to the luck factor because some levels start with the fat guys in the first room, and I brought a melee weapon instead of a gun from the last floor. And even if I did have ammo for it, most rapid fire weapons only have like 15 bullets, which is used a lot when you just spray into a herd of enemies, hoping to hit the people with the guns.