It's long and it's involved. The writing is good and the animation aint bad. The choice of music during certain scenes however really give it some dissonance between the 'action' of the music and the nonchalant way that Derpy goes through her life story. I paused the movie at 4:30 to write this review, because this was a prime example of that happening. She "knows she'll have to live with this for the rest of her life, but doesn't mind anymore..." The music was so inanely over the top that I kind of lost the feeling and emotion that had gone into the writing.
That being said. This was posted, I'm now seeing, a while ago. So eh.