I think I would give it 3.5 stars if I could.
It's an entertaining book, but not entirely believable. And I'm not talking about the obvious stuff, because it is science fiction book after all. But the bad guys (of which there are surprisingly a lot) don't really come across as real people. The hero's tend to have this problem too, they seem a bit to good and to skillful.
However I enjoyed reading it and I will probably read more peacekeeper books.