This piece is a great example of your progress as an artist. Many of your Deviations have harsh lines, but here you have made it feel more natural. The flow of Luna's mane and tail is well done and mostly characteristic of MLP, and you have matched details of her character nicely. I really like that you made the correct parts of her mane and tail transparent. And the shading is quite good too.
You really bring the viewer's focus to Luna through movement: the moon's light towards her and the way the stars seem to flow with it. Blurring the background also brings her forward in the picture.
There are a few things you could continue to work on: keeping a steady hand when drawing your lines, and adding a bit more detail to the ground. I can see that your lines are a little bit squiggly, that could be because of the software or tools (pen tablet, or mouse) you used, or you may just need a little more practice. By adding details, I mean that you could add some grass by her hooves and maybe some bushes too. I do not think that Equestria is that flat! Adding in some distant hills, too, could add to the appeal of your picture.