Everybody in the Western world knows who Pac-Man is - that yellow blob whose only purpose in life is to eat smaller blobs and avoid ghosts. A huge hit in the arcades about a thousand years ago, its addictiveness and cuteness have assured it a place in modern folklore.
The Gameboy version is a faithful replica of the coin-op, with one major difference (apart from the lack of colour) - the play area can be shown in two different ways: either as a full-screen mode, with small sprites, or in a magnified mode that only displays a section of the play area, but in much clearer detail.
Starting with three lives, Pac-Man clears each screen of the small dots to progress to the next - large blobs make Pac-Man invulnerable for a short while, so it's the best time to munch dots and ghosts.
I don't think this game really cuts the mustard any more; it's certainly a classic, but the gameplay never varies and the graphics, while accurate, don't stretch the capabilities of the Gameboy at all.
The choice of screen means that either the sprites are too tiny, or that you can't see the whole area! Still, if you were a fan of the coin-op, it's worth a look.
Pac-Man's simply gameplay makes it an ideal arcade conversion for the Gameboy. The two screen modes is an excellent idea, and since this version packs all the features of the coin-op (including the intermission screens), Pac-Man fans are bound to go nuts over it.