The point of the above is that I don't remember the previous books that well, but this one stands well enough on its own. Characters from previous books are woven in -- this is not an episodic series; Anton's life is an arc running through. But you could start here if you really wanted to.
It has a minor sequel-flaw, in that halfway through the characters have to sit down and say "Okay, we're not fighting that monster from book 3, and it's not another thing like we met in book 4, so... it must be something brand-new!" (Remember that scene in The Hallowed Hunt?) But this is brief.
I think the author's didactic tendencies may be rising. Again, I don't really remember, but one interjected lecture about the effect of the Communist Revolution on the balance of good and evil is enough. Two is too many. Any lectures about vampire physiology are too many.
Going on about the Russian character -- sure, I read non-US authors for the non-US point of view, but it's better conveyed through Anton's pop-culture references than through his speeches. I love that he reads Pratchett and Strugatsky and J. K. Rowling, and listens to Azerbaijani rock bands that I will never, never know about. And there's a Russian joke with the punchline "Shall we wash these children, or have new ones?"
None of this background stuff, good or bad, overbalances the plot. The ending comes off as sudden, but I think that's a translation issue. Things happen, one after another, and they need that thunderstorm sense of repeated shock. The translator doesn't quite catch it. Allow for that, and it's a solid story.