Howdy! I'm Aubial. Simply ignore my critique if you can't take constructive (or maybe at some points a bit harsh) criticism.
Alright. Judging by this piece, I'd guess you're fairly new to drawing, or at least new to digital art. I'll give you a few pointers that might help you out a little bit.
First of all, it's good to have your art appeal to the eyes. Solid, bright colors aren't going to look right on a landscape. It's good to put diversity in the color you use, try blending in a few shades in so it's not a bunch of dull colors. If you take a look outside you will see that there is no thick black line on the horizon line, or around buildings or mountains. it looks much nicer to keep your outline small.
If you look at a mountain, you'll see that it, suprisingly, isn't just a cone with a cone of snow on top. Your drawing will look much nicer if you put more effort into the environment, besides just a few pointy mountains on flat grass.
Sorry about how sloppy this review is, I hope you will forgive me. I'm just trying to give you a few pointers. If this doesn't help, try tracing a couple of landscapes. Eventually you'll get the hang of the shapes.