The Nintendo version was terrible. Ok, that's out of the way.
The C64 version was a lot of fun. You move around the city, busting Slimers for cash. Repeat until the city gets flooded by so much PK Energy that the Marshmallow man shows up. Run between his legs, beat the game, use your hard earned cash in new game plus to buy a better car and more gear. Make sure you buy ghost bait every game so when the ghosts freak out and rush at one building, you can stop them from Voltroning and crushing a major part of New York (and losing you that precious cash).
Also, the chiptune soundtrack is weirdly annoying and yet incredibly satisfying. You'll basically hear the same few notes for an hour, but it will be a heavenly trumpet call leading you to glory and franchise riches. Fun times.