Dont like the yellow, but everything else is nice.

 Thanks for criticism. Will try to consider in future :)

The gradient looks odd. It might look better if just the one pixel in four was used for the sky.

 Very good, I like it!

 Very minimalist, I like it .

Yes i agree, the yellow is too toward green and needs more orange in it. also it would helped if you toned down the value just a bit.

I don't like the shade of yellow you have chosen.  The gradient dithering is kinda just ok too, but overall, I like the aesthetic of the piece