This book follows the usual 'Voyager finds a rumor that they might get a way home' plot, with Janeway willing to chance destruction of the ship for a quicker way home. That's reasonably consistent with the show, I guess, but since we know there's no real danger to the ship, I don't think it works as well to show how serious Janeway is about getting back home.
The idea of a huge battle involving everything that a civilization has to put into it and lasting for a very long time isn't too new, although Ragnarok perhaps goes a bit further toward showing how far they've gotten, stripping every last ounce of metal out of whole planets to build ships for the war.
I liked the look at the alien race that spoke in imperatives--it's always fun to see how authors will try to make a really different sort of alien. The ones in the previous book (The Escape) were more or less like extra-bureaucratic humans, so it's nice to see something a little more alien this time.
Overall, this was a reasonably fun read, though maybe not quite as good as its predecessor.