The first part of your song, up til 00:15 sounded quite lacking. Composition-wise, you really shouldn't have both the flute and the cello playing the same exact notes. Or if you were to do so, have some other instrument contrast against them.
The second half is alright, although I think you could have incorporated the flute and cello from the first half into it.
As for the technical aspects, there's definitely room for improvement in mixing. However there aren't any glaring issues at hand here.
Keep working at it!