(I got an ARC through NetGalley, in exchange for an honest review.)
I very seldom read "fan" books—i.e. featuring characters from TV shows/movies. I think the last one I read was an X-Files novel, some 20 years ago, and not even its original edition/language. So keep in mind I may not be the best person to judge such stories, and try to consider them from my point of view as a reader in general.
Also, it doesn't help that I've only seen one season of Doctor Who. I love the series, but never managed to go further, because of reasons. Shame on me. Whatever. I was spoiled about a few things, and not spoiled about many others. However, I can at least give an opinion about that, and I'm happy to report that the present novel isn't of the crumbling-under-spoilers kind. If, like me, you've only seen the first season, or not many more episodes, then you already know that there was a Time War; that the Doctor is a Time Lord, and that they do regenerate upon death; that he had an important role to play during said war; and that the Daleks are, well, the Daleks.
You don't need to know more to read and enjoy Engines of War, and it won't spoil the whole series for you either. Which you may consider either a good thing (like I did), or a bad thing (if you're a seasoned Whovian who wants a lot more). Although I admit I didn't catch a few references to events that happened in episodes I didn't see, I don't think it's really a problem. This lack of background is specific to me anyway, and the story functions well even if you don't know anything about those events.
Here, the Doctor meets a new companion, Cinder (or, rather, Cinder does meet the Doctor), a young woman from Moldox. Her planet and surrounding solar system was attacked and ravaged by the Daleks, and she's been part of a doomed-to-fail resistance movement since childhood. When their paths cross, she jumps on the opportunity to leave this dying world, but soon comes to realise that it's not so easy as to just go away and find another place, because the latest Dalek-made weapon is one that would totally change the fate of universe, both in space and time, if it were to be deployed.
This book reads fairly easily, and much like an episode from the series. I wasn't always completely happy with the writing, which was sometimes a bit too "tell-not-show" to my liking, but such occurrences were actually quite sparse. There are plot hooks and cool concepts (the possibility engine, the time-wiping weapon), there are twists, we meet with a Doctor who's more jaded and hardened than the one I got to know (the Ninth one), yet still displays a lot of the "Doctor-isms" I liked on TV. The author managed to make scenes very easy to visualise, including the TARDIS's and other sounds—not so easy to do without falling into the realm of ridicule. The Time Lords are shown as just as fearsome as the Daleks, in their own ways. And Cinder is a resourceful companion for the Doctor, not just some girl tagging along. She has a reason to leave, a reason to fight, has picked useful fights along the way, and her humanity is an important anchor for the Doctor, one that deeply contrasts with Rassilon's cold, distanciated views.
This wasn't the best novel ever, but it sure was worth the few hours it took for me to read it.