I mostly agree with you, MeisterH. For those who have not read the novel and would like to read a (long) review, you can find my review here:
How he captured Itami's personality is probably the best part of the book (according to me).
I feel the same way, and I believe Miah wrote the same about Jeschonek's portrayal of Itami. I also really liked the way Jeschonek captured Irina's "Siren of Samarkand" persona. The novel itself felt somewhat unfinished because of the teaser at the end. Based on the end for this book and for Operation Night Eagle, it seems that there is a larger agenda in place. Hopefully, we'll eventually find out more about that agenda.
If you're interested, here are some of my theories based on the two books, though I should note that there are major spoilers for anyone who has not read the two books yet.