Review:
I had read "Once a Hero", which is something like the 4th of 7 books in the Serrarno series a long time ago on a used book. Then I got a couple more, again out of order from the Baen free library.
I quite liked them so I took a chance now at paying the author and getting the whole story by reading the three omnibus editions.
Conclusion: I did not like them as much as I remembered but they are still pretty good. They do suffer a bit of the hypercompetent scifi hero syndrome, but at least they are not guys.