Really now...
Like Iceleaf said, low quality graphics, shitty plot and crappy english.
However, I think this could be awesome if you executed it in a different manner.
+Add some background music to make it more dramatic
+Improve on drawings, not nessecarily animation. Could do still-pictures with subtitles to immerse the viewer
+Expand a lot on the script.. I mean, really now.. "And he became a zombie."
+Darker environments
+Creepy radio static & the likes in the background
If you'd do this and keep the "you are the demon" moment you'd get one hell of a flash with an awesome mindfuck at the end.