I don't know much about spy novels. I've only heard about this trilogy because it's also classified as low fantasy (there's no magic, but it takes place in an invented world). It was a nice change from what I usually read.
There's major m/m and mentions of f/f. The m/m is sooo~ good, especially in Book 3. ♥ I'm glad I waited until all 3 books were out to start reading this story.