You had me at samurai mecha shmup ^^ The hero is very convincing and I could imagine myself scrolling through his world ^^ Regarding the play mechanic, doing a shmup with big sprite is doable:
- sword slash could reflect bullet to damage ennemies
- if you have a big ship/hero, you should have a BIG shot (possibly transparent like a cascade of water^^)
Very very solid graphically, character design is there :)