I think Zelda 2's biggest issue is the time it released. There are plenty a Zelda fan who grew up in an exclusively 3D era of game design. Zelda 2 released in a much more primitive, less player friendly era of gaming. For a large chunk of gamers who grew up during that era and were subject to...
Its a bad game.
Zelda 2 is from an era of unfair difficulty and primitive game design that makes it less enjoyable than more contemporary Zelda games. It's far from the only NES game to suffer from that sort of primitive design, but it's more noticeable due to the comparisons it draws to its...