Someday...

Composition
The structure of the piece is simple and effective. The pony's plight and reality on the bottom and his dreams on the top.

The latter portion could be slightly larger, which would allow for more room for detail, but the current look gives the idea of the dreams being sufficiently "big." Furthermore, the position of the bubble makes it a centrepiece of the picture, drawing attention and only secondarily relating the actual grim reality.

A slight decrement is a certain lack of detailed background. The heavy grey sky currently used give the picture additional sense of grief and despair, but some generic background could have a merit as well - for instance, a small hut in the background could show us the vastness of the field the pony ploughs and further add to the overall impression. An unwelcoming (even desolate) landscape could achieve this as well.
The current weather could also benefit from an expectable fog which would again stress the horrid living conditions of the protagonist. The field, slowly vanishing in the haze, would probably serve better than the current sharp horizon.

Major players
The obvious three major parts are the plough, the real pony and the dreamt pony.

The plough looks sufficiently realistic. Its surface, littered with many signs of frequent usage, speaks volume about the daily life of the pony. It could perhaps show a bit more wear at places indicating that the pony lives in such poor conditions that he can't afford even the most important repairs of his most used instrument.

The rope between the plough and the pony could be more stretched. This would show the force necessary to move it and give the picture additional air of exhaustion. The cord could also be thicker, seeing how the current one begs a question whether it would withstand the constant strain.

In the same moment, the plough serves as a good metaphor for the "shackled" way of life. It literally holds the pony, preventing him from achieving his dreams.

The pony, Day, is very well detailed and thought out. The overall colour scheme delivers a sense of a pony tied to the earth. The selected shades of brown and dark red work great with the ever-present mud, but are sufficiently different so that the pony doesn't blend in with his surroundings completely. This again serves as a good way to relay the feeling of a character that may be used to the environment he's in, but certainly doesn't belong to it by design.
The actor's appearance is that of beaten, broken colt. Shadows around the eyes and the strained posture show the hard work he has to deal with.
The mud, which the pony obviously ignores, signifies the way the actor is used to the terrible living conditions he finds himself in. A small injury is seen as well, being a nice detail that accents this even more. The terrible state the character's mane is in as well as the malnutrished body are two final, broad strokes that shows the plights of the poor pony.

Day's visage conveys many inner feelings even without the thought bubble. Regret, shame and broken dreams. His eyes show weariness, but still retain a hint of an inner spark. The furled brow gives the air of unyielding force of will. The character's internal world of dreams and hopes is surely the one thing that keeps him going.

The pony's pose could probably - again - show more force behind it. The colt almost seem to tiptoe through the mud. There is almost no visual indication of effort being made to move the plough.
It is possible that the though was to make the pony look as if he's paused in his work and lets himself be lost in his fantasies. The pony's pose - i.e. being in mid-step works against this though, at is not easily sustainable.
Moving the pony down - burrowing his hooves in the ground a bit - would probably solve the aforementioned pose issues.


The third part - the fantasy - is a great contrast to the despair-filled image below. Even though the colour scheme remains similar, the clean golden tinge speaks volumes about the prosperity and great living condition the pony would hope for.
While the general appearance is a complete opposite to the grim reality, the pony's face retains the same vigor and tenacity of his real self, connecting the two with the aforementioned willpower. This makes Day a character that is apparently not a wimp or quitter. Moreover, a hint of positive emotion - even tenderness - which the imaginary Day seems to posses is a great detail to show our protagonist's softer side.


The same two problems remain with the fantasy portion as well - that is the background and the pose.

Seeing how the though bubble remains relatively small, the former doesn't play as big of a role. A simple red wedge on blue background is a nice colour contrast that lets the pony's body and mane shine while it speaks about the vigour the pony seems to radiate.

The later is more of an issue. Day's front hooves, clasped around the microphone create few problems.
First and foremost, the microphone itself is partly obscured, which makes the viewer take a good few seconds to think before he realizes what it is the pony is actually holding. Furthermore, the overall look of the microphone contrasts with the rest of the picture by its lack of details and general rushed feeling of execution.

The character's front hooves also raise the question: How is he standing up? The microphone stand's angle shows no support, nor are any of Day's hooves preventing his imminent fall in any way.
While this seems as a crucial oversight, the fact that the lower part of the pony is not shown softens the blow.

As a whole
Overall, the picture conveys its ideas well. It is full of emotion and details, while still remaining relatively simple in its composition. The repeating motif of plough, being omitted from the fantasy, as well as countless other details serve to the artist's credit.
There are few questionable decisions (lack of background) as well as a couple of oversights on the part of the poses. The picture could easily show much more vigour and thus, more desperation.
However, these decrements serve as a minor decrement in the face of the many decisions set well towards the goal of the picture.