Going and beating all the modes in the game lets you see how well designed the game is, things like the minor items like flashes, pepper spray and such are actually great things to have and only in harder modes do you realize how effective they are and are forced to find out who it's effective on.
Overall the best game on ps1, not as a one time experience, there are much grander games for a one time experience but 100%ing it I would say it's the best one.