Haha, well, once you get the hang of the regular mode it gets a little boring, HELL mode is basically the same but with extra zombies (ooze)
You can use an automatic machine gunnnnnnn 
Incentive enough? The new weapon is sweet, and the game is more fun on HELL mode. But yeah, playing through the same thing over and over and memorizing it was probably the only way I managed to beat it. I think I beat HELL mode on my 4th try though. In case no one wants to know what happens ->
I was really surprised when I reached the elevators and still had a hand grenade to take out the majority of those enemies. I figured I was a goner, but I managed to pull through. Ammo was scarce this time through