While sonikku's version is generally better, this version has major differences. Since it throws boomerangs as normal sprites you can have normal sprite interactions (spinjumping, eating with yoshi, etc.). It also uses less graphical space, which is nice. So yeah, it works, it's different, and it's approved.
(Edit: added screenshot)
there already is a boomerang bro uploaded to the site, and it seems a bit better than this one
It depends: the other sprite is better in that it uses an extended sprite for the boomerang, but this one allows for interesting platforming sections (since you can spin jump on the boomerangs it throws).