The original is fun, and actually a lot different than the hitman games that came after. If you can play it do so, if not its no big deal. Some major differences are that the map pauses the game and does not show the location of anyone (other than 47), there is no reward for a clean mission or penalties for a messy one (unless you kill cops or civilians) and there are some missions which are intended to involve you in the raging gun battles that in other games only happen when things go bad, and you have no way to sedate targets; your supposed to kill guards and then hide the bodies. Also no rating after a mission, instead it changes how much cash you earn and what weapons are available for next mission.
Man who hesitates is not only lost but also miles from next exit