If you're a fan of Star Trek (the original series), this book ought to tickle your fancy. To talk too much about the plot would give away a really big and delightful surprise, so I won't go beyond the marketing text on the back cover.
If you read the back cover, you'll find quite possibly the dullest description of a Trek novel that you can think of. Essentially: Kirk & crew run into a ship of a barely warp-capable species they'd encountered a year or so earlier. The new ship has advanced incredibly in only a year's time. But Kirk had not given them any technological help. So, has the Prime Directive been violated somehow? That's it. Riveting, right?
Not really. But the book becomes riveting pretty quickly. For starters, this species was not, in fact, featured in any episode of TV Trek (nor any of the non-canon stuff, as far as I'm aware), so it's kind of interesting to learn about this new species. But there's a really awesome (as in, Sense of Wonder) TOS-style secret hiding behind the technological leap, which it would be a crime to give away in a review. This secret also gets more interesting as more is revealed.
So, A+ for a cool sci-fi plot. Characterizations of the regular characters are mostly spot-on, although I did often struggle to find exactly where the William Shatner voice in my head would pause dramatically. No matter, it's Kirk -- you can tell. Uhura gets some good "screen-time" (as it were), and the TAS character Arex has a few good moment as well (this novel takes place seemingly after TOS but before TAS - so, in the latter half of the Five-Year Mission).
References to TOS episodes are sparing but effective when used ("Devil in the Dark", in particular). The writing style is effective too -- Swallow likes to show off a bit when describing the sense-of-wonder stuff (and it reads a touch too florid on occasion), but the style is just transparent enough for a quick, fun read-through.
I haven't caught up on my post-Destiny reading yet (and that is going to take a long time), but I'm happy that there are a few James Swallow novels waiting for me on that list. Well-recommended.