Considering that it's the newest game it practically has to have more content than any other game. However, getting through the game didn't take me as long as Wind Waker or Twilight Princess even with all the side content. I think it was just easy- it was long though. I have no way of knowing this for certain, but I feel like if I had not played other Zeldas before Skyward Sword that the puzzles might have been harder. As it was it was the easiest Zelda game for me to beat the first time around, but that has to have something to do with experience.
I think in terms of 100% it might be the easiest Zelda just because of drowsing though. The dungeons really were short too, but I think it's because they put emphasis on making the surface dungeon-like. Personally I'd never want to see something like the surface again, but that's just my opinion.