Turnbull is a decent storyteller. Japanese is a language blessed with few syllables, and, due perhaps to the ideographic writing system, a tendency for names especially to repeat the same ones with minor variation. In spite of this, Turnbull does a good job in taking the slew of warriors and battles with confusingly similar sounding names and giving sufficient personality to them that a number of them begin to come alive on the page. In achieving this he does take some curious shortcuts, though, for a historian. He has an habit of presenting dubious source material uncritically, especially the Heike Monogatari, an account of the Genpei War which is as much a work of literature as it is history, and one which is quite clearly fictionalised.
Perhaps my accusation is merely that Turnbull trusts his reader too much. The most interesting observations about the samurai I gleaned from reading this were the ones Turnbull alludes to rather than says aloud: that the samurai were, for most of their history, as much a social construct as a military class; that much of their history their conduct seemed almost as performative as it was soldierly. The samurai, like his sword, is one part warrior, one part romantic idea. Finally, that romantic ideas are all good and well, but in the end it is never sentiment that carries the day: it's relentless, cruel pragmatism, backed up with the aggression needed to create one's own luck. It's Tokugawa Ieyasu.