I admit I am an unabashed fan of Tanya Huff. Whether she's writing fantasy - the "Quarter" series - witchlit - "Blood" and "Smoke" series or the Valor books, of which this is the third (you need to read the other 2 first to make sense of this one), Huff makes her characters come alive. Gunnery Sergeant Kerr is as tough a military scifi heroine as you could want; but all the backfills and quirks of a real personality are there, tucked away in mental asides. Its got all you would want if you like Davids Weber and Drake or Elizabeth Moon - plenty of action, blood, militech and surprises, but the secondary characters are fully formed, even if they are going to end up in a bodybag, which in this universe shrinks to a pocket-sized cylinder because "no marine gets left behind". Clever, gripping and as realistic as space opera is ever going to be - in this timeline anyway.