You could actually say it is. It follows the same examples of "The Legend of Zelda" where it's grid mapped and has dungeons as well as boomerang, bombs and 6 sages. In fact, it even has the same goals, involving a evil character trying to rule the world.
However, there are so much difference as well. The art style is unique, weapons are different, minigames and a new world. You also have different side quests too. You can also tell the developer are trying to make fun of this with the loading screens resembling other games and the unique scripts and characters.
So i wouldn't say it's a rip off, kinda like a tribute. Anyway, rip offs are normally really badly made. Is this that bad?