just completed this quest. 6 deaths and a few resets during level 9 (~15 deaths total). as many have said the quest is pretty easy, except for level 9, who's difficulty feels unbalanced with the rest of the quest - although once you know where to go and which battles can be avoided isn't that bad. its a bit harder than the 2nd quest. i really enjoyed the level design - some of my favourites of the contest. and it feels really NES authentic. the poison heart gimmick is really cool, though I agree with Nightmare that increasing the drop rates for certain enemies might be a good addition. i disliked the stronger wizzrobes being the same colour as their regular strength counterparts, and the shooting darknuts would make more sense throwing swords.

other than tossing some more or harder enemies in the earlier levels, i think the main issue is that it is easy to upgrade your equipment early. if you could limit when the player grabs the blue ring, letter, and upgraded swords to later in the game the earlier dungeons would be a lot more difficult, and would balance the game a bit more.

all your old man clues were really cryptic, i don't think i understood the meaning of any of them - but had no issue finding anything. i thought the stalfos clue was to do with a maze path (ESES), but never found a corresponding maze.

i would have liked to see some more upgraded bosses, and was disappointed with a few levels where the dungeon boss was the same as the dungeon mini-boss - at least bump the power of the main boss if they are going to be the same enemy type.

overall i had a good time playing, and if the difficulty was turned up a notch i'd see this being a strong contender.