After having played Kuzen for the entire day, I think his Ult is okay at best. What would make it better is if it instead of knocking people back it knocked people up and inward towards his shell. I also think you should be able to use his 2 and then his ult to have his 2 last the entire duration of his ult. Making it so that you can utilize this reflection damage a little more efficiently.
Kuzenbo really does feel lacking.