I have no Idea what to say
It is really hard to decide where to start this review.
Ok... As it seems to me it is a typical shouen-type (probbably misspelt it) cartoon, with ninjas or samurais in it. I can tell where you got the inspiration for the main character. It felt pretty generic.... I couldn't grasp the feeling of the story or the pacing of the story and events. It didnt give me a impression, the impact that something is happening.
The writing is cheap, and I mean seriously cheap Filled with the most typical one-liners of battles - like ''I will avenge the people''. It isnt well thought out writing and your story-telling abilities are not the best. To help the pacing, story you must make that the viewer would ''get the feeling'' of your cartoon. Maybe if throw a short flashback of the ''Avenging character'' the plot would seem more plausible. The character needs motives, you cant just put labels like "He is bad, therefore I must kill him". Seriously - More character development and pacing.
Second of all the voice acting was below average, and you cant balance the volumes of the voices I couln't tell what certain character said. The subtitles saved it... but not by much.
Although the animation feels not right (did not hold my beliefs), it was rather.... decent. The style was wierd, but acceptable.
Bottom line: Terrible writing, Bad audio, decent animation. Author had no Idea for a actual plot, author intended a animation of a kakashi-looking ninja killing a bunch of stuff.
But in the end - It kept me entertained.
What you should do: Dont force stupid jokes (zelda (if you do, just make it short)), have more character development (motives, backstory), fix the audio, and think of pacing more. (some Scenes rusher, while other scenes were dragging in it).
I see a lot of potential in you.... Good luck!