I loved it, too. One of my favorite NES games, and ESSENTIAL in an NES collection. Yeah, it strayed far from the rest of the series, but I don't have a problem with that because it's still fun. The added RPG-elements really added to the gameplay, too.
That final dungeon, though, is a real pain the ass. You have to survive the trek there (including going through that gorge where the Moblins throw rocks from the top of wall, and that canyon where you have like 5 forced enemy runs), then you have to survive the dungeon itself, and fight not 1, but 2 dungeon masters. And the normal enemies in the dungeon are tough, too. So hard. I've only actually beaten the game once, by luck. I can usually make it to the final dungeon, but I can't beat it.