This is certainly cute, and you have a flair for more than one style as evidenced by this, it's both cute and a little awesome, especially the mane.
The main problem here is evident: The legs. While the detail & shading is nice, they are FAR too small and skinny for him, and I feel you thought you were running out of space when you made the legs, try and take a bit more time to judge what you've got next time!
The haunches were a bit of a problem for me too, but that's just because the style is a bit off for me, I'm used to seeing the leg curve into the flank, not stop abruptly, so this could kind of count as an aesthetic complain and thus very disregardable.
The face was another biggie. It is so off-shape and under-colored that it felt crudely plastered on in reference to the rest of this, and I really feel it could have been a bit smoother than this. The mouth and nose were very difficult to find, use a brighter or larger lines to better enunciate where they might be.
The cutie mark is oddly flat and un-shaded when compared to the rest of this, you took much less time on it than the rest of the piece, but the whole thing suffers for it. Try and keep the whole piece in the same level of effort, it really pays off in the end.
The ear was a big thing, it is too lumpy and huge for me to consider part of him, you need to better size it to fit in with the rest of him, and thus making a better piece. the ear lines & shading need to be bigger as well, if you want them to fit in.
Pretty much my favorite thing about this was the mane & tail, they are amazingly detailed and they look great for it, but they kind of feel out of place next to this pony, you have to try and keep a consistent level of concentration throughout your piece.
All in all, while this had a few redeeming factors, it remains that you have quite a bit of work to do before you reach truly great standards, but I know someone who can at least put in that level of effort, even only occasionally, can try a little harder and amaze us all! 6.5, because I'm challenging you to get better!