This was a nice and fun read that I probably would have enjoyed much more if I remembered ANYTHING about the first three books other than that I enjoyed them and someone had a gem in their navel.
But Carson does the "first girl in the army" routine  well, the story itself had a reasonable number of twists and turns, although some of them felt contrived and there was a fair amount of hand-waving the politics. On the other hand, the characters were awesome.
I just wish I remembered more about the books that came before.