Melodies are ok, maybe a bit basic for this style of music, but it doesn't reduce my listening experience. I dont really like the sound of that piano however. I'm sorry, I can't really describe why, but there just is some piano sounds that I dislike ><.
I would've preferred some more ambient noises, especially at around 1:00, to give it more vast and spacey feeling. Also a bit more variation in the chord progressions would've helped.
Mixing, as far as i can tell is quite good. Though I don't think that I have the most trained ear for that. But I think that you kinda overdid that bitcrushing at the end :P
In the end I'm really not that sure that what rating I should give to it. I wouldn't listen to this on it's own, but as BGM in a game it could work.
Anyways I hope that you found my ramblings even vaguely helpful :P