A:RES is not too bad; you just need to know where everything spawns from and be ready. Ammo isn't really a problem either if you know where everything is. First time through the game, though, is extremely tough going. But repeat playthroughs are easier.
I finished the game legitimately much later on PS2 and using the analog sticks - made things a lot more do-able control-wise as opposed to using the D-pad on PS1. When I first played it on PS1, I died often and had to cheat through the last few levels. The game was cool as hell, though, because it made me want to keep going to beat it. It was tense all the way and good fun.