As someone who has studied Soviet history and has a love of Shostakovich's music, I had high hopes for this book which were not disappointed.
The personal biography of both men was sufficient without overwhelming me with information, while the politics and music were very well explained. The greatest insight was that of Stalin's attitude to culture - his normal image being of a brutal, ruthless tyrant who I hadn't imagined was as cultured as he turned out to be. The intense interest he took in the cultural elite, and the fates that befell many of the Shostakovich's contemporaries, were very well brought out. The cat-and-mouse style games the artists, composers and writers were forced engage in, and the intense pressure they worked under was very well evoked - Mayakovsy's suicide and its ramifications being a notable example.
Overall, for a potentially quite dry and academic subject, this was refreshingly accessible without simplifying the issue too much. The relatively small selection of Shostakovich's work that is discussed in detail means that the focus is retained well, and gives lots of scope for more detailed biographical or musicological reading.