This book is essentially a well-written and well-argued defense of the British Army's combat record on the Western Front during World War One. As the title suggests, it is not exhaustive nor definitive: it focuses on the British Army, on the Western Front, on the tactical level. However, the author's lucidity, knowledge, and extensive bibliography make "Battle Tactics" a suitable introduction even for someone with only a passing familiarity with the Great War. For those who are more familiar, it will offer some refreshing counterarguments against the "lions led by donkeys" canards directed at the Allies.
The popular conception of World War One is, essentially, the Somme, or perhaps Verdun. Human-wave attacks on entrenched positions cut down by withering artillery and machine gun fire, with some gas thrown in for good measure. Meanwhile, generals and their staffs sat around in chateaus drinking red wine and cavorting with French girls, pausing only to telephone their regiments to go over the top. The problem: the Somme was in 1916, only about halfway through the war. In the words of Young Jeezy: and then what? Griffith wants to tell you all about it.
Griffith describes in considerable detail just how hard the British officer corps worked at all levels of command, often at astounding personal risk, to develop the tactics needed to break the Western stalemate. He compares their efforts favorably to the Germans, whom he portrays as often one step behind their Allied counterparts in this regard. He also covers technical innovations--including of course the tanks but also many lesser-known improvements to artillery, aviation, optics, etc--and how they resulted from the tireless dedication of British civil servants, industrialists, and private citizens. Again he compares this favorably to oft-lauded German equivalents. He also explicates the institutional changes in the army. For instance, the Somme represented the debut of a new volunteer (rather than professional) army which was rapidly improved by dedicated officers who then used it to win the war.
It need hardly be said that Griffith is fighting an uphill battle against nearly a century of contrary belief. Most modern people essentially base their morose view of the Great War British on Blackadder Goes Forth and a host of literary figures they probably couldn't name. Griffith doesn't address most of them by name either--preferring to address their criticisms rather than their persons--but he does single out B.H. Liddell Hart for a good drubbing throughout the book. You can always consult the footnotes to find out who, exactly, Griffith is arguing against, but for practically any modern reader the views being challenged will be their own.
The book's scope is purposely limited in time and space, so you won't see too much analysis of e.g. what it meant to the British Empire (as opposed to the Western Front) to have the ancient imperial army basically wiped out between 1914-1916, or the strategic effects of Russian offensives. Unfortunately the narrow tactical focus sometimes just doesn't do the subject justice. Griffith glosses over the tremendous human cost of the fighting, and the book's focus can create a false impression of the importance of tactical versus strategic considerations in the outcome of the war. The author's criticisms of the Germans are often too one-sided, for instance eliding their demonstrated superior ability to disseminate and coordinate adjustments to tactical doctrine throughout their forces. The author does acknowledge most of these objections, however, and there has been plenty written about these subjects elsewhere, often readily cited for the interested reader.
Overall, I recommend "Battle Tactics" for anyone interested in World War One. Military buffs with an interest in tactics will find it particularly appealing, and it is a good starting point for someone who wants to increase their knowledge about WWI beyond their schoolbooks.