Still awesome after almost 15 years.
Awesome gameplay, the ability to copy your opponents attack is brilliant. It also ensures that the game is never the same twice, a rare feat in those days. Lots of hidden areas that requires you to have a certain type of attack to access make for some good puzzles. They even threw in some really fun mini-games and a "museum" that allows you to change your attack before starting a level. Great graphics, great music, and a pink balloon that eats monsters!
It's abnormally easy, you can easily finish the game without losing all your lives. It's kind of on the "cutsey" side, but whatever. Other than that, it's pretty much perfect.
The Bottom Line
A true NES classic in the same vein as Mario, Zelda, and Metroid.