Since everyone knows how to play it already (get all the dots while avoiding the ghosts), I'll get right to it: this is a terrible version, obiously put together by someone who didn't care. Pac-Man and the ghosts move very slowly, and when you eat a power pellet the ghost change color (but not expression). Finally, none of the bonus fruits from the arcade game are there, just a plain yellow block which is explained as a "vitamin box" in the game's manual. Whatever...
The graphics are just awful, with blocky characters and tons of flicker from the ghosts. See the screenshot on this page? The reason you only see one ghost is because the other three are in the middle of flicker mode, so they don't appear on screen. The sounds are bad too, with none of the arcade sounds -- just a generic bong-bong sound accompanied by some tweets and beeps. The control also feels floaty.
After all is said and done, this version is a slap in the face to Pac-fans, and the worst Pac-Man game in history. If you want a 2600 Pac-fix, you'll be better of with Ms. Pac-Man and Jr. Pac-Man, two far superior arcade translations.