The Language of Bees was at least a moderately intriguing mystery novel, although it appeared to have had its ending rudely amputated and replaced with a gimcrack cliffhanger. This book is all falling action, with little mystery and no intrigue. (Spoilers, not that I recommend that anyone actually read this book.)
The creepy Reverend Thomas Brothers who dominated the first half of the story is eliminated with minimal fuss early on. The new antagonist who loomed behind his swift rise and subsequent fall, an intelligence agent who aspires to be the new Mycroft, is tolerably competent at wreaking some havoc but never very interesting, particularly in his own tedious chapters. Holmes and Mary, separated until nearly the end of the book, do next to nothing other than tend to their charges, Damien and Estelle respectively, fretting endlessly over logistics of doctoring and childcare.
The only person who does any notable deduction in the entire novel is Mycroft, not that you would realize this from his P.O.V. chapters, which take the form of endless worrying over a pseudo-mathematical equation which describes the situation in terms vaguer than the proverbial spherical cow. He pops up again after every possible drop of pathos has been wrung out of his faked death and tries to give the book some semblance of action in retrospect, but it isn't very successful.
The reviewers on Amazon seem to be very impressed with the character of Robert Goodfellow, who apparently reprises a very similar character in one of King's Kate Martinelli books which have completely failed to hold my interest every time I have looked at them. I am much less so, although his backstory of WWI, shellshock, and recreation of himself as a sort of wood sprite is probably the strongest part of this sorry book; it doesn't him any more interesting in the main action, such as it is, and his role in the finale is so WTF that I probably would have thrown the book across the room at that point if I hadn't been listening to it in audio format. Mary Russell may think it wonderfully symbolic and mythological that he insists on wandering into a hostage exchange, not helping anyone in particular, getting himself very predictably shot, and finally killing the tedious Mycroft-wannabe whom everyone else was working so hard to keep alive to be questioned, but I do not agree. This scene was so stupid that it made me retroactively hate the rest of the book even more, and I was already hating it pretty thoroughly.
The God of the Hive has cured me of the habit of reading the Mary Russell books whenever they come out. I suppose, on the behalf of my groaning to-be-read shelf, I should thank Laurie King for that. Ugh.