You know,
This is a good start if anything. If anything, you need to really work on your art style. It seems too "square". What I mean is that it looks like a very young person drew it in paint. Granted some of it was good looking, but taking the time to truly evolve your art style into something much more detailed and fuller will definitely make your animations much cleaner and prettier. I'm not sure what your method of drawing is but I suggest maybe investing some money into this if you can if not invest the time and effort to make it work if you can't spend money.
Sound was very clean. No clipping in the music or sound effects. Everything seemed to be the same audio level. Didn't have any problems there. Always a plus.
For the animation I found it to be very smooth. Very little to no chopping or clipping. Good job there. I liked the idea of the story, but had very little plot to it. You should look into making it into something that will allow the audience to connect with. Give the flash a sense of emotion and engage your audience with a mood instead of just pure combat. You see too many combat style animations these days. It just feels like I'm watching another damn Dragonball Z animation.
Overall, I see potential and say keep pushing forward. Develop your story. Add emotion besides fighting. Take the time to make your art evolve into something much fuller as it has potential. I thin its a start. Not the greatest, not the best. I say it was worth it if you learned something from the experience.
3/5
5/10