Ahhhh, Mike Tyson's Punch-Out!!!, one of the best boxing titles of all times. 
The game is so great that it costs upwards of 20 dollars even though there is a
much rarer version without Mike Tyson which might go for 20 if it's boxed. This
was one of the first 90 games released for the NES, and is one of the best.

Graphics - 10/10
Wow! For a first generation NES game (or even NES games in general) this game
has superb graphics. The sprites are large and colorful, and Mike Tyson even
resembles his real-life self. This game uses the MMC2 mapper chip (Mapper #9)
which allows for the huge character sprites to be shown without massive
flickering and slowdown.

Sound - 8/10
The sound is great, and fits with the action very well. It really gets your
blood pumping. You have all your standard boxing sounds (bell ringing, etc.)
plus theme music in parts. Don Flamenco's music stands out in particular...

Gameplay - 10/10
This game has some of the most challenging and entertaining gameplay for the
NES, and that's really saying something. The game starts out simple, and
gradually gets tougher until the near impossible fight with the ear-chomping
boxer himself, Mike "Kid Dynamite" Tyson. Split second reflexes are a must to
last simple past half a minute, because his special "Dynamite Punches" are one
hit knockdowns. 

Replay Value - 10/10
Even after defeating this game, I seem to play it all the time, and I'm sure
anyone who has played the game will know what I'm talking about. Challenging
yourself over and over trying to defeat tyson with a KO (or even defeating him
at all, even with a win by decision) is an extreme challenge and is well worth
the hours of practice you'll need.

Overall - 10/10
A game that deserves to be in every NES collector's collection. 

A quick piece of advice : Search Flea Markets and the like. I found a Near Mint
boxed copy with the instructions, poster, and even the letter from Tyson
(a $70 - $80 value) for 5 bucks.