Played it and beat it. Impressions below.
The bad:
1. Please, turn on the "Smooth Vertical Scrolling" rule.
2. I don't know if this is a general ZC bug, but I get a very short blip at the end of each custom sound effect. This happens after every slash of the sword, for instance.
3. Should be obvious enough:

4. The highlighted tiles are solid and shouldn't be:

5. Take a gander:

The door tile two tiles directly south from Link is wrong. This door tile uses a purple floor, but it should use the gray "entrance mat" floor.
6. I'm not sure exactly what I did, but I think I pressed the down key after defeating the Level 1 boss (at the end of the Elite guy's speech). When I did, it took me directly to the beginning of the boss battle. I beat it again, pressed up at the end, and it was fine.
7. Level 1 just drags on and on and on for the first dungeon of the game. I would have fallen asleep in the tunnels if I hadn't accidentally pressed the Windows key (which minimized the game in order to bring up the start menu). Level 1 would be great without the tunnels in my opinion (even so, it would be the size of a normal Level 3). It honestly felt like you were trying too hard to make Level 1 "perfect."
8. I found that the blocks for the block puzzle before the ladder (I believe) have different combo types. Some are "None" and some are "Push (Wait)". Pick one and apply it to every push block.
The good:
Very colorful and detailed, good music, plentiful SFX, and a good variation of enemies. I found no game-ending bugs. I really like the interconnection of the dungeons and overworld. Excellent first boss.
Although the "bad" section is far longer than the "good" section, do be aware that you put out a good, quality demo. The "goods" easily outweigh the "bads" (so you should be happy with yourself). 😊