Toll of Honor is broke into 2 books, and spans the period from the end of the Battle of Hancock to several months after the Battle of Nightengale, paralleling the last few chapters of SVW, all of FoD, and the first part of HiE.
Brandy Bolego is not the heroine of the book, but is the mechanism on which the book moves forward. The book tells the previous stories form another point of view. Bolego is occasionally the main PoV character, but not always. While she is the center of the story, the story isn't hers, she's mainly just near the events happening around her on a grand scale.
As such, the 1st portion of the book doesn't really give us anything new, but tells points of view which show how badly the actions of the Manty opposition parties, and their use of the Young court martial, freeze the RMN when it should be able to sally out and take the fight further into Haven controlled space and make true dividends before the new Havenite leadership reforms and learns it's job.
The RMN is initially able to use it's most ambitious pre-war retaliatory plan to follow up the initial Havenite strikes, but further action is stymied as the RMN needs funding and supplies beyond that provided in it's yearly maintenance and training budgets to continue fighting, and to ramp up munitions and parts production to supply their forces in an environment where active operations are putting years of scheduled peacetime use on parts in mere months, let alone that required to repair battle damage. Fleets ready for battle sit for half a year - half a year that gives the New Havenite leadership time to sort itself out.
The 2nd half is 6th fleet taking the fight to the Havenites on the "northern" theater, pushing to Trevor's star. Several systems are quickly taken, and the Havenite PoV characters are universally jr officers elevated 4 or 5 levels to command positions they know they are unprepared for, and sadistic People's Commissioners elevated even further.
Before Nightengale, all the RMN runs into is pickets of a handful of BBs with escorts or smaller, none of the wall. We find out about "collective guilt" - every Havenite Navy member is being forced to serve - and serve well - or their family will pay the price. No one can afford to look like they are being defeatist or not doing their duty, for fear of reprecussions to their family. Nightengale is the first time 6th fleet meets wallers, and the ill timed trap there is the first sign of the Havenite's wall - and their command teams having learned their jobs.
After several smaller actions, the Prince Adrian (as well as other ships) are rotated home as constant warfighting has worn them out, despite the heroic work of engineering staffs and support ships.
The back thread of the Book is Harkness and Bancock's relationship getting closer and closer, ending in Harkness taking a debilitating round for Iris in a boarding action, which results in their getting married. (not in the book).
Points of Note. The PRN Tonnare class BC is mentioned for the first time in cannon (it was mentioned in a Jayne's filler paragraph), and 2 new CL classes - Conquerante and Gardienne (but the Conquerante could be the previously mentioned Conqueror class).
In addition, it was highlighted that Haven's Battleships did not field capital missiles, indicating they used CA/BC class missiles or another intermediate class missile. The implications of which are that while they have the tube count to go toe to toe with a Waller, their smaller missiles do not do the damage of the larger ships, and have weaker penaids - so even with a moderate numerical advantage, BBs can't go toe to toe with an SD. BBs would probably need a 4 or 6 to 1 advantage in the missile space to get parity with an SD (where BCs need a 8:1 ratio to get parity).
Overall, a good read, but noting new, just filling in the spaces in the story from interesting perspectives. Definitely worth the read, but does not move any existing bars.
(As is the hyper velocity bleed-off making a stated problem actually irrelevant)