wow! great drawing of celestia, i really like how you drew her hair/her face, her horn and her crown, everything is very realistically drawn, and i really like how complicated+vibrant her hair look like! its so amazing!
her eyes are drawn nicely too, with a good shine on them, and they have a nice, realistic expression, despite the characters cartoonish nature (obviously).
last but not least, i like her pose, and that small smile on her face.
also, her colourful hair and the simple(?) background make a nice contrast, which adds more strength to this already awesome picture.
what can i say? its a great drawing, mate!
keep it up! you're great!