I guess this was a big seller when it came out because it's a pretty comprehensive account of the Civil War, all in one volume.* It's a lot to work through. The Civil War is an intimidating subject, because 1) a hell of a lot has been written about it, from a lot of perspectives, and 2) it's a subject with a lot of passionate enthusiasts, so no matter how much you read, there are always learned people around telling you that you didn't get the REAL story, and you should actually read this *other* (there's always another) 1000+ page tome, to get the real scoop.
So I took a chance on this one, because it's been mentioned to me a few times. It's not bad.. gives a lot of good background information, doesn't appear overly-biased from what I could tell, answered a few questions I had, and integrated the Civil War into my own evolving sense of that era.
WHAT I LIKED IN PARTICULAR:
1) A lot of detail related to why England and France declined to diplomatically recognize the Confederacy, and what practical implications it had on the Southern war effort. (e.g. the South couldn't order munitions from foreign suppliers, or warships from British or French shipbuilders) It was touch-and-go a few times, when a Southern victory here or there would get the British foreign office considering recognition, but other considerations always intervened against it.
2) Probably the author's strongest point was his analysis of how the 1860's -more than many other time periods- was an era when new technologies brought more powerful weapons onto the battlefield before military strategies had evolved to account for them. As a result, you had soldiers fighting with rifled-bore guns and cannons nearly to the standard of World War I, but using marching formations and maneuvers left over from the Napoleonic Wars. Likewise, you had (at least at the beginning) ironclad, steam-powered ships fighting with tactics from the age of sails. This made the conflict much bloodier than it could have been, because one unintended consequence of this was that conditions GREATLY favored the defending forces- which was more often the South (where most of the battles took place), even though the offense was a much more industrialized, better-financed North.
Related, McPherson highlighted the importance of Northern river ships in the overall conflict- something I had no appreciation of before, but which was actually decisive at Vicksburg- arguably the turning point of the war. Southern fortifications along the Mississippi and her large feeder rivers were built on an age-old premise that ships could never take down a fort alone (i.e. without troop ground support). This had been true up through the Crimean War, but new cannon and armor technology reversed the maxim, and made the Western theater of the Civil War an area of complete domination by the Northern navy.
WHAT I DIDN'T LIKE:
All the belabored accounts of every troop movement and flanking action, etc, of nearly every major battle. McPhereson isn't the only historian to subject his readers to this order-of-battle stuff, but here he fills at least two-hundred pages in an already-long volume. I just don't know anybody who enjoys reading ground tactics in a book not specifically dedicated to that subject. I may be way off here, but I think most lay-readers of history are interested in the broad strokes, and putting the larger events into their proper context... not talking about which hills were steeper than others, and how some particular meadow was harder to defend against flank attacks than another. Unless you know that particular geographic area in great detail, WGAF?
The good outweighs the bad here, though, and I felt McPherson brought something new to the table, by showing a clearer path of how the Civil War influenced fighting in World War I. Specifically: the later battles of the Civil War began to employ trenches and barbed wire fortifications, which came into much wider use in WWI, and really shaped that character of that war. Also, the nascent use of field medics, the use of elastic fiat currencies to finance the conflict (both sides), and the philosophy of "total warfare" (i.e. attacking civilans, instead of limiting conflict to two opposing armies in a remote battlefield) all predicted things to come fifty years later.
Other goodies included: the bit about Lincoln's limited suspension of Habeus corpus, the
schizophrenic (is it non-PC to use that term in this way?) character of Missouri (was it a slave state or not?), and a good digression about the special political significance of Kentucky.
Overall, I recommend the book.
*after the book's success, the author negated the "all in one volume" selling point by writing two more volumes.