This is a general review of the series. It does not contain spoilers.
I managed to go as far as the fifth volume of the series. The series starts off as an interesting and easy-going mystery with a couple of plot lines that intertwine and fit together quite nicely and add to the suspense. Furthermore, the plots and the main characters’ backgrounds touch on issues that are in the focus of public discussion, too. However, a few volumes in, the plotlines become somewhat repetitive and I found it harder and harder to stay focused and intrigued by the progress of the story. Eventually, with the emergence of another book on my horizon of interest, it was easy for me to let go. I do not like to leave a series unfinished but I must say there isn't much to draw me back, although it is an ongoing story and I will not find out how the story ends.
The characters and ‘sets’ of the series are generally well-built and more or less diverse, although more depth and detail would help for them to be more authentic and truthful; this need - in psychology for the characters, and in details and precision for the sets (by sets I also mean the organizations described etc.) - becomes bigger with every new volume. The pace of the series is easy and balanced, but at times it slows down a tiny bit too much due to too much theorizing on the part of the main characters, or rushes unnecessary and too intuitively through key moments. The reference to ancient history adds a distinct pleasurable flavor although the reader should keep in mind this is a work of fiction – as always in such cases that use known facts in the plot.
As the series progresses the plot in some of the novels would unravel in a somewhat predictable pattern, and that could tint the read a bit monotonous. In general the diversity of tasks and locations makes up for it. However, I would have appreciated more resourcefulness and detail with regards to the riddles and the way of solving them – at times the latter is too intuitive and leaves the reader with a sense of dissatisfaction. Also, the main character’s special ability is set as a foundation of the plot in the first novel but later on it is somehow left behind to some extent.
Despite all the above remarks I still found the first few books of the series interesting and exciting, and inviting the reader to do some further reading on their own. One important feature that I enjoyed is that the characters have integrity throughout the series (at least until novel #5), and at the same time they do develop and change as personalities, thus making the plot alive and authentic. Having written that, however, I once again stress that deeper psychological profiles of the characters would contribute greatly to the plot.