Yes, this stretches the boundaries of Whitestar, and I for one think that is a good idea. Star Sailors adds Magic Girl heroes to the sci-fi universe of Whitestar, and honestly they are not much goofier than Star Knights when you think about it.
This supplement is short and quick, decently written, and gives you enough background and "stuff" to run a Star Sailor centered game, or just add one to your group of wandering stellar adventurers.
My only complaint is that each Star Sailor only gets a single power beyond basic energy blast abilities, and I would have liked to see a bit more variety or advancement, either a menu of powers to choose from or at least singular abilities that leveled up. But i guess I could always write my own... ah the beauty of OSR gaming.
A solid 4 star supplement.