15 hours non 100%, and about 20 hours 100%. Mostly because I kept dieing on the Cave of Ordeals X_x Oh and I had trouble with a poe at Lake Hylia, so I could probably do it in like 18-18 1/2 hours.
25-30 hours to complete the main quest.
It's really not that difficult of a game, most enemies can be defeated in one swing of the sword.
Bosses' weak point easy to find and take barely any hits.
Puzzles are pretty clever and can be quite challenging though.
I posted earlier, but that was way off. I'm almost at 40 hours, only at the City In The Sky! I wasted a bunch of time because I was looking for the lady with the bomb arrow game. I decided to just to do the temple, and it was a good idea because I found the game and won it.
Can't remember what my time was for my initial play through. Probably pretty bad as I just messed around/explored and stuff. It took me 31 hours for my three heart challenge.
Well if you are counting just beating the game my quickest time was like 12 hour or so I think. I forget it is been a while since I played it. Beating the game getting everything including Piece of Hearts, Poe Souls, the Bugs, and the Hyliah Loach and unlocking all the lures was under 70 hours. I also did kinda of a lot of time wasting stuff so I could probably have done it a lot faster.