My very first video game other than Mario/Duck Hunt.
The bosses are killer, and to me Zelda 2 is not as child-like as some of the other Zelda titles. For example Zelda Wind Waker for the Game Cube. I don't want to bounce around on leaves like a little pinball, I want to use my sword and magic to crush bosses. That is what Zelda 2 for the NES offers. You even learn different jumping attacks as the game progresses.
Two down sides prevent it from being a 10. One is that the music is not what you would hope for in a classic Zelda game. The second point is the map screen which you travel between locations with. The graphics aren't good and it doesn't help the game.
Overall: a big 9. If it just had better music I'd have given it a 10. Recommended course of action: you can play it for free online.