It's a good animation in a lot of ways and again yes sad and depressing things shown in animation can invoke emotion like no ones business but that also tends to erode you a little on the inside too, emotionally and artistically . Personally I don't like depressing things and strive to avoid them, but I do see the need of them for story and such in forms of entertainment. If you continue down this road take time and do happier stuff to balance the dark it would help balance and even improve your repertoire. Mind you when I say happier stuff I didn't say it had to sunshine and butterflies, but it could be twisted or dirty, as long the humor is all in good if you are into that. Good luck to you in your future works.