Having just finished the last book of the series, I can't help but paraphrase that old TS Eliot quote "This is the way the series ends - Not with a bang but a whimper". On the whole, I enjoyed the series very much. The Heris Serrano books were well written and (despite a strange preoccupation with the minutia of breeding horses) contained many memorable sequences. Esmay Suiza was, to my mind, an even better heroine than Heris and her first two books are the strongest on the series. But then it comes to the last two books, and it just seems to be a mad rush to get to the last page. Elizabeth Moon has lots of good plot ideas throughout the series - The Benignity, the Bloodhorde, the mutineers, the problems on Altiplano, Sirialis and Copperwalls, the Rejuvenant vs, Aegist problem, the NewTex Militia etc., but she seems to have tried to cram in as much as she possibly could, and the effect is to leave far too much up in the air. What happened to the fugitive confessor? Why DID Arash Livadhi do what he did? What happened on Sirialis? All these questions (and many more) go unanswered.
In my opinion, Elizabeth had enough plot ideas to fill twelve books, not just seven. And if she didn't want to write so many, one can't help but feel she should have left half of her ideas out in the interest of streamlining the story.
Having said all that, I enjoyed the series and will adding her, alongside David Weber and John Ringo, on my list of American authors who deserve more UK recognition.