There are some nice ideas here that could be further developed and worked in more contrasted ways. You reproduced very well the idioms of typical NES soundtracks! :)

It really feels like you potentially bite off more than you could chew. Most of these tracks are ptty okay, not bad at all, but some of them are lacking and feel rushed. 

Good 8-bit-vibe Job!)))

This is certainly not meant to be mean. But I feel like having just one song and working on that would have gotten you a better result. While most songs sound true to the GB/NES and its limitations, I feel most songs sound played save with just one melody repeting itselve and reversed. I kind of wished for something more. None the less you've nailed the challange with every song. So kudos to that.

Short, but sweet tracks! Great job! I do like the retro gameboy vibes.