Things move slowly quickly in the universe inhabited by Jack Campbell's The Lost Fleet series. Campbell's tales of interstellar war between the good guys from The Alliance and the bad guys from The Syndic Worlds are tales told at a snail's pace, setting up brief episodes of battle that pass all too quickly.
Valiant is the fourth book in the series, which has been engrossing throughout. Yet this one feels like the lesser of the books. It starts with the Second Battle of Lakota and manages to make the replay of the only skirmish the Alliance fleet's relatively lost since Black Jack Geary took over command of the armada, last for almost half the book's length. If you love turn-based battle simulations, then those 100 plus pages are going to entertain you and keep you guessing at how Geary will pull the Alliance's fat out of the fire. Even if you don't like simulation games, you'll enjoy the ride.
These battles, done as realistically as physics will allow in a universe with the conceit of interstellar flight through space, have been the focus of the series. No Star Wars-like battles with fast and faster spaceships dueling like World War II era airplanes. No, hours and days take place before battle can be joined. Then, the chance to score hits on the opponents lasts seconds, if that, before velocity shoots your ship past their's. It takes time (and pages) before you can curve around for another engagement. It all feels VERY 'real' in a way. All in all, this is military SF at a high level.
Then we get the second half of the book.
It's a 'character development' section of the series. After three books, the love/lust triangle between Geary, his ship's captain Tanya Desjani, and Senator Victoria Rhone, Co-President of the Callas Republic, takes half a book to get resolved. At least in terms of who's gong to end up with who. It's handled awfully awkwardly by a writer obviously much, much better versed in the ways of physics than writing bad romance material.
Interspersed with the girls-and-guy stuff, we get a move by the conspirators in the fleet to make one last gasp attempt to dethrone Geary. It's done through computer worms. Several waves of them. And it's all so unbelievable that the security guys aboard the command ship Dauntless can't track them, even though the team admits to knowing about many, many shadow-nets running through the fleet's main computer systems. At the same time, they've been able to detect how the aliens (secretly monitoring the fleet and having started the Alliance-Syndic war a century ago) have been piggy-backing on their computer systems. Unh-hunh.
Ultimately, I think the biggest issue Campbell has to face continuing this series is the unbelievability factor. The fleet sailors and marines think Geary has been a gift from the gods. His winning against all odds at Lakota has surely made it impossible for any but the stupidest to believe the fleet would back any coup attempt. It's not rational. They'd be better off letting him work his magic and get the lost fleet back to Alliance space, then assassinate him there.
With his need for character development behind him, I'm hoping Campbell focuses in on the remaining battles to get Dauntless and company home. Peace will ensue and then Geary and humanity can turn their attentions to the aliens that caused all of this grief, death and destruction during his 'extended' life-time. Let's say there's another two books to go in the Lost Fleet series. Then he can start Humanity's Hope.
In other words, Geary's romantic fulfillment is still a LOOOOOONG ways away!