This is actually pretty cool, but a few things are wrong. The cutie mark colors (on the rainbow bolt thingie) Are supposed to be red, yellow, and blue. And the cloud also looks a little too puffy looking. Also the eye color looks a little too dark. It looks a little bit more like a red color. And the colors on her tail don't look very lined up. And I think the orange color looks a little bit too much of a brown. But you did get some of the colors right. And I love how the background looks, and the fact that you added the scar on her face.
Nice shading. The scar was a nice touch, though the colors on the tail or usually more vertical-ish if you catch my drift. The ear is rather large, but you drew some amazing hair. The back legs-- the cutie mark leg is pretty rectangular, and the one in the background is pretty small. The blood is a pretty cool too. Her eyes are more pinkish though, like Pinkie Pie's hair color. The orange could be oranger, it's more of a brown shade. I've never seen her presented on a cliff, it's pretty original. Overall, I gotta say it's a pretty decent Rainbow Factory representation.