I think he meant he beat the boss in under 20 seconds.
I didn't think it was extremely easy the first time I played through it. I literally spend days figuring out the Forest and the Water temple. And those were days in my Christmas break when I spend alsmot every waking hour playing the game. I eventually asked a friend how to get through the last part of the Forest Temple (I had no idea you could push the room around), but I solved the Water Temple myself
Some of the boss battles were pretty tough at first, especially Volvagia. I think I died 15 times the first time I played through it (in total, not just against Volvagia). I would say that apart from the NES games it's not really much easier or harder than any other Zelda game.