Vorpal Blade by John Ringo and Travis S. Taylor
This is a military science fiction story. The United States navy with the help of he Adar an allied alien race convert a nuclear submarine into a warp drive spaceship. It is the classic subs in space theme from science fiction. Man the torpedos.
The first part of the book is about training and selecting the crew for the ship, The Vorpal Blade. It goes over the specifications of the ship as well as the combat suits which the space marines wear called Wyverns. There are also a few other tropes from science fiction thrown in, the teenage genius girl with the alien pet, and the brilliant linguist. If you like military hardware it is kind of interesting.
The second part of the book is space exploration. The crew learns how to use the warp drive, they make some observations about astronomy, and they refuel water and oxygen from a gas giant. There is some science in this book. Travis S. Taylor, one of the writers, has several degrees including a Ph.D. in Optical Science and Engineering and a masters in Physics. The first half of the book is not that combat oriented
In the final part of the book, the space marines fight the tentacle crabs, then they save the bipedal space hamsters from the evil demons. The space hamsters, or as the author says, space chinchillas, need a lot of help. It is up to the marines to fight various beasties like armored insects, laser firing dragonflies, and dragon beasties. Of course the marines save the day, but not without some casualties. John Ringo who has written a lot of military science fiction novels does excellent combat descriptions.
This is a fun book to read. It is not particularly realistic, the space marines don't use any rocket launchers, flamethrowers or other very heavy ordinance in fights; it would end the battles too quickly. Just bullets, combat suites, grenades, and knives. It is a sequel to the book, The Looking Glass, but only references the Dreen, there are no actual evil alien Dreen in this book. The book already has a sequel which I plan on reading called The Claws That Catch.