Not horrible, buuuuut...
The cartoon is well animated, the special effects are excellent, buuuuut... Well, there's really no story, no plot. It's really just a fight scene with no reason whatsoever behind it. Why are Sonic and Nazo gripped in mortal combat? How did this all happen? What is Nazo trying to accomplish? Putting at least a little bit of plot behind a fight scene makes it more exciting for the audience because they're more invested not only in the fight itself, but the outcome. No plot, less excitement, because the audience has no reason to root for either side.
If you truly intend to make this a real series that people will enjoy, please consider adding at least the bare minimum of plot. You know, something like; Nazo has escaped from Hell and wants to take over the world and only Sonic possesses the power to stop him. Once you have a plot established, even a bare-bones basic one, it will raise the effectiveness and impact of your combat sequences immensely.