Did you just sample the source for the intro? Either that or you did an exceptional job recreating those lo-fi strings. I think it would be more fun to create your own version of it. Don't think it would result in an instant rejection cuz Yoshi's Island is not Square Enix. But still it feels superfluous. So let's start at 0:39. There is something overall about the arrangement that feels plodding. Partially the beat which feels a bit plain Jane. But also I would say the sustained bass part saps any potential energy from the arrangement. For a downtempo song that wants to groove the bassline needs to groovify more.
The drums almost feel like they want to be dubstep but the pads and lack of an sharp aggressive bass don't follow through with that feeling.
Source usage wise everything seems to be in order, even when you don't use the melody outright you seem to be following the chord progression.
For a 4-minute song (let's discount the intro) the pacing and energy is pretty samey and it kinda had me looking at my metaphorical watch. There weren't any surprises for me, things that made me sit up and say "Oh!", and the groove wasn't so strong that I was dancing in my chair. I definitely love downtempo arrangements, too, this track just needs more melodic and rhythmic hooks to draw the listener in.
I'm not a huge fan of the use of the source string part in the main body of the song. I just don't like the sound of them. Try replacing them with a different string patch or something different entirely and see how that sounds!
Also, fadeout ending, you'll definitely get shit from the judges for that.
So yeah: overall I would try for a more groovin' arrangement with more rhythmic elements and some ear candy, things that grab the listener's attention. The mixing could be a bit cleaner and sharper but I think the writing and arrangement is a better place to focus your energy first. And maybe do something about those strings. Hope this helps!
/mod review