One of the first things you'll notice about the Confederation of Valor is that the universe Tanya Huff has created has it's very own distinct feel: While it certainly has its roots in the most generic of Science Fiction, the series inserts dozens of unique touches into the text which give it a unique, refreshing twist from the norm. From descriptions of typical station life to quirks of technology, the story establishes a strong voice which leaves it distinct from other offerings in the genre.
However the real strength of the story is that, while it is Science Fiction, it doesn't lean on it as a crutch. First and foremost, this is a military story which just happens to take place in alien, futuristic locales against non-human foes and featuring the occasional strange technology. The plot is focused on the characters, moves forward with the characters, and is resolved by the characters. No Deus Ex Machina in the guise of a sci-fi technology is used to handily resolve problems, with such technology instead serving as the window dressing for some impressive, engaging stories.
Despite the fact that each of the three races within the marines has a distinct set of peculiarities, every character is quickly developed beyond those facets. Instead of being cardboard cutouts of the typical characteristics of their race, those characteristics are simply used much the same way another author might use a cultural background for a modern-day character. Each person introduced is distinct enough to stand apart from their peers very quickly, painted in broad strokes which serve to separate them in the reader's mind until the author has time to fill in the more subtle points of their personality.
To be quite blunt, this series is a fine example of a modern day pulp fiction. Each novel contains enough information that you don't need the previous novel to get what's going on, and each story is largely self-contained. The series sets out to entertain and do a bit of world-building without descending into the need to be more than a simple, engaging distraction.
It succeeds very well. It won't challenge your perceptions or slam an Aesop down your throat, but it'll entertain you quite a bit while you're flipping the pages.