Finished: Star Trek Vanguard: Summon the Thunder [SPOILERS]
Plot-wise, Summon the Thunder focused on Starfleet's continuing efforts to unravel the Meta-Genome while also investigating the alien ruins uncovered at the end of Harbinger. Added to the mix are the Romulans in the form of a bird-of-prey, Bloodied Talon, commanded by Sarith. I liked the Romulan chapters because the running of a cloaked BoP reminded me of all those submarine movies and books, especially whenever the Bloodied Talon was in danger of being detected and the crew went into a "silent running" mode. On the flip side, I didn't like how their story ended, with Sarith destroying her ship after losing warp drive and on the verge of being detected by a Klingon battlecruiser. The impression I got from their final chapter was that the Bloodied Talon was going to go down in a blaze of glory, launching a surprise attack on the Klingon ship, but the epilogue and a quick check on Memory Beta proved me wrong. I actually imagined them disabling the enemy ship, then boarding it and stealing all of its anti-matter and warp drive components.
The Shedai Wanderer, the mysterious alien that's responsible for so much of the death and destruction in Summon the Thunder is so, so intriguing, especially their as of yet unexplained connection to the Tholians. This being not only kills Captain Zhao of the Endeavour (along with a number of other Starfleet personnel, including one very, very, very unfortunate Denobulan) and clearly destroys the ship, it also blows up an entire goddamn planet! You could also add the crew of the Bloodied Talon to that list, since the destruction of Palgrenax caused the Romulans to lose their warp drive. It even tried to add a second planet, Erilon, to the list only to be foiled by Starfleet Corps of Engineers.
Overall, I'd give the book a solid 9.