Gwyn as a heroine has Abby from the last book beat by a mile. Jason, on the other hand, didn't impress me as much as Hugh, but that's probably being unfair. Gwyn is on her own and has a son to raise, yet she has a quiet strength.
Harry the assassin is threatening enough to seem real, not that I have come across any assassins in my time.
Gwyn's son is a darling and it's sweet to read the scenes where he plays with Jason. I imagine that Thornton's being a grandmother of 5 in real life (when she wrote this*) gave her the motive to give the little man his own personality.
The other female character has personality, too--more than Gwyn, actually. Judith is VERY funny! Quite a firecracker. And her avowed fiance, Jason's brother, likewise shows more personality than Jason. Grandmother Radley is a pistol, too.
Good story. Not 5 stars, but not 3 either. But why the title "Princess Charming"? There is no princess, and no connection that I remember to "Men from Special Branch"--but then it's been a few days since I finished the book and went on to read 3 more. My memory is a sieve! (Was Jason a friend of Hugh or Richard? I can't remember...headslap!)
(*She passed away in 2010--so sad.)