I'm going to be brutal here.
Truthfully, I thought a lot of the ship designs were weak. The main enemy was nothing but variants. Couldn't you of put some more effort into making them look better.
I was watching it and it all seemed great through the intro and past the Zero Wing intro.
From the stand point that not everyone is an artistic god, your style was lacking. The battle scenes could of been more unique, maybe some different camera angles.
Voices would also help a lot. Get some friends to do the voices. You were also taking an already over played plot and stripping it.