It's been a number of years since I read Grave Mercy, the first book in the My Fair Assassin Trilogy by Robin LaFevers. I didn't take the time to write a review, but I rated it a 4 star book. I do remember enjoying the coming-of-age story regarding assassin nuns in a fictionalized Brittany where supernatural gods/saints interact with the real world.
The second book in the trilogy Dark Triumph just didn't hold my interest. On the one hand, I couldn't put it down, on the other I found myself speed-reading/skimming just to find out what happened. I know I missed a lot of details, but I have no interest in going back to pick up what I missed.
I don't know how much of my opinion is due to the specific book and how much of that is due to changes in reading taste (after a number of YA heavy years I seem to be reading more traditional SF). I do think I will eventually give the last book in the trilogy a try.