The good things for this first outing of a promising new detective series are : an interesting set-up - the Tsar's former special detective is released from the gulag by Stalin to find out who really killed the royal family, and where the Tsar hid his treasure - and the interesting setting of Stalin's Russia, of course; the well fleshed-out persona of the detective, Pekkala, and the other characters, and the general high standard of the writing.
However, some things disappoint : the identity of the killer is obvious early on, as is the location of the Tsar's 'treasure map'; the way the treasure has been hidden uses an element of the Romanovs' terrible fate that is fairly common knowledge now, and Pekkala's attitude towards Stalin in the end scene is frankly incredible.
Also, several of the main characters have been given names that have great resonance in this period - Kirov, Kropotkin, Kolchak, Mayakovsky etc. Why? Why not use nondescript names? You wouldn't expect to read a crime novel set in Nazi Germany, with a group of characters who happen to be called Rommel, Bormann, Doenitz etc. And despite a good sense of the period, there are some basic errors that could have easily been avoided - the 'Emka' car didn't exist in 1929, the Tokarev wasn't general issue then either, the Nagant's special cartridge is mentioned, but not the more significant cylinder to barrel connection vis-a-vis gas sealing, an automatic is called a revolver, and the author confuses the term 'White Army' with the Czech Legion.
The above quibbles are minor, but without wishing to give anything away, there's an incident where Pekkala fails to recognize someone that is simply unbelievable.
Having said all that, there is a lot to recommend in this book, and I would be interested to try the next instalment in the series.