don't run!

I like this picture. The white flower looks especially pretty for some reason, and the combination of pink, green and yellow works fantastic. The hottest cherry areas, however, clash too much against nigh-primary green, as does the purple "cutie mark", was it called?.
The same-coloured energy from the horn would work better as a dynamic substance and less like a piece of cellophane with a different outlining or none at all, to distinguish it from more solid masses, and a more vivid colouring.
The sunny lens flare in the pony's face is a clever way to call attention to it, but ultimately hurts the eyes with its agressive shine. I would suggest that you used the yellow iris primarily instead, toning down the rest of yellow hair and the surrounding flares, and then applying a slightly stronger flare (like the ones to the left of the face) as the eye gleam.
The lineart's a little dirty at places; the shading and perspective are a little off, but in a work like this, with colour masses as the main interest, it gives it a nice traditional Picasso-disciple painting look. All in all, it's a nice piece to look at from a certain distance.
I hope I've been fair!