As Fiasco: The American Military Adventure in Iraq, 2003 to 2005 showed, author Thomas Ricks has no problem offering harsh criticism of those in power - and here, he presents a variety of lacerating critiques, but also strong compliments, of a variety of military leaders.
The overall thesis for this book is, I think, an accurate one - that generals of today are often not relieved for their failures of leadership or actions, and instead allowed to finish their careers at the expense of the nation's objectives.
Granted, Afghanistan has seen several commanders relieved in mid-stream, so there has been a move toward quicker changes...but, those changes (McChrystal, McKeirnan, others) were driven by civilian leadership, and Ricks argues that top military leaders should be more willing to fire their own high-ranking subordinates.
Generals like George Marshall and Eisenhower receive the bulk of the praise, for managing personalities and strategic missions during World War II, and being willing to make changes when need be. Many division commanders were fired during WWII, but were later given a second chance at command. Unlike 2012, a 'firing' was not a career death sentence, but an admission that an officer was not right for a certain job at a specific time.
Now, a battlefield relief is the end of a career. Ricks mentions Col. Joe Dowdy, a Marine colonel relieved during the 2003 Iraq invasion. Basically thrown out of Iraq, Dowdy didn't exactly retire in disgrace, but he certainly was not offered a second chance to redeem himself.
Part of this is the corporate culture, born in the 1950s, of the military that Ricks describes. Like all corporations, it became the interests of the leaders to protect their peers. Sure, junior officers could be relieved with no issues, but once a general was in the club, it was easier to let them ride out a career - as Ricks writes, LTG Ricardo Sanchez thought about relieving Abu Ghraib's failed BG Janis Karpinski, but decided not to, since her rotation was almost up. That's a terrible reason to let a leader remain.
The book covers almost 75 years - comprehensive, but maybe a little too much time. Some sections, especially Iraq in 2003, seem a bit rushed (though his other books cover that ground, and should be read anyway). Other sections, especially a long and very detailed account of the Battle of the Chosin Reservoir, seem to be a little too specific and maybe off the subject. It's a dramatic battle account, and it deals with massive failures by Gen. Edward Almond, but the tactical focus sometimes doesn't fit with the rest of the book. But, this very specific battlefield example allows Ricks to make a necessary good-bad comparison between Almond and the successful Marine Gen. O.P. Smith who was fighting on the reservoir's other side.
And, like the rest of the book, the Chosin narrative is very readable and always interesting.
There are a few surprises (depending on how well read you are) - Gen. Norman Schwarzkopf and Gen. Colin Powell don't come across very well for their hesitant and insecure plans during the Gulf War (which was no surprise to me); George Patton, a successful battlefield commander, played his role very well - with Ricks giving a lot of credit to Eisenhower's calming influence.
This is a good introduction to this topic, though its scope makes it a little too broad for deep knowledge. If you followed up with Eisenhower in War and Peace, Westmoreland: The General Who Lost Vietnam, and The Commanders, among many others, I think you'd flesh out a lot of the specific stories that Ricks can only give so much info about in these pages.
Finally, Gen. Tommy Franks receives much of the harshest criticism - and it's all completely valid. He is held up as the kind of tactically-oriented general that Ricks has little use for - yes, he can manage a battlefield, but has no concept of the larger strategic goals that a general should be aware of. So forecasting any Iraqi insurgency simply wasn't his problem, and the Tora Bora hideout of Bin Laden was not a tactically important goal. Gen. David Petraeus, on the other hand, is complimented for seeing the big, strategic picture that will develop over many years.
An excellent book - not THE definitive resource, maybe, but with the history and personalities involved (I didn't even mention Westmoreland or MacArthur!) how can it be?
UPDATE: I'm just finishing The Liberator: One World War II Soldier's 500-Day Odyssey from the Beaches of Sicily to the Gates of Dachau, in which Gen. Mark Clark comes across very badly. Clark's failures are mentioned here, certainly, but not in that much depth - so The Liberator would be another good additional resource.
Full disclosure: I read a complimentary review copy (and am briefly cited and indexed in The Gamble: General David Petraeus and the American Military Adventure in Iraq, 2006-2008 for my own Iraq reporting).