It's incredible how you transform an old game into a whole new art! The side scrolling style is gave a real charming detail in this art. The use of strong and cold colors are beautiful and the place is inspiring. I truly loved it!
It would be great if you let a bigger version of it to download so we could see better the details, but it's okay.
Also, I envy you for doing such beautiful trees/plants your shading really is amazing. The spiders are very cute (IMO) they don't seem to be dangerous. XD
Focus seems to be a bit tiny - mainly on Link and a small bubble around him, then a bit on Ganon's face. Perhaps unify that focus between them.
The detail on Ganon's face seems to clash with his rather simple arms and torso area. I would have loved to see some ornate armor plating like in the source concept art and maybe some more detail on his arms. The amount of detail on the environment and Link just further highlight a lot of the simplicity on Ganon. Though, great job translating his face to your own original work.
WOW. This is absolutely incredible. It's always fun to see artists reinterpret old 8-Bit games - they're so simple-looking that there's a ton of room for creative reimagining. This look really fits into the Zelda universe well...it would be awesome to see a Zelda II remake that looked like this.