it's extremely DIFFICULT. I have been playing this game since it was like 2 years old, and I still haven't been able to beat it! That proves how wimpy modern N64 platform games have become, since I am able to easily defeat its 1996 counterpart.
But the graphics for this game and its sometimes-cartridge-partner, Duck Hunt, seem quite advanced for 1985 and 1984 (respectively). At least compared to games like Excitebike (1984) and The Legend of Zelda (1986). The music is nice (although the dungeon and the castle music gets repetitive) and sound effects are cool. Once you've beaten this game, there's no need to play it anymore, but if you haven't, like me, you'll be wanting to keep playing until you beat it, and frustrated if you fail.
But this game is the same age as me, and I still play it at my friends house if they're hogging the Super Smash Bros. (I haven't beaten it yet.)