The book is an enjoyable read, easily approachable for someone who has never heard of the Punic Wars but still satisfying for someone starting out with a good knowledge base. O'Connell makes excellent use of his ancient sources and marshals his information into a coherent and compelling narrative.
The writing flows well and is easily followed, making the book a fairly quick read. I found some of O'Connell's turns of phrase a bit bizarre, though. At one point, he says that republican Romans followed the "Warholian rubric" when it came to turn-over of their government officials. He also describes Hasdrubal Barca's escape from C. Claudius Nero as "a vanishing act worthy of Bugs Bunny," though he goes on to assure us that Nero was no Elmer Fudd! While I assume many folks reading this book will understand what O'Connell is talking about, I somehow doubt references to Andy Warhol will make much sense to someone reading Ghosts of Cannae fifty years from now. Admittedly, I suspect readers even 100 years from now will be familiar with Bugs and Elmer, though. As 20th century cultural artifacts, Looney Tunes are worlds more potent and long-lived than anything Andy Warhol ever did.
While I am no scholar of republican Rome, I felt that O'Connell's treatment of the history was detailed, well informed, and fair. In only one place did I quibble with one of his claims--that annoying modern assumption that the speeches made by the ancients and recorded in histories were mere whole-cloth fabrications created by ancient historians to make a moral point. Referring specifically to Livy, O'Connell says:
Ancient history is replete with such speechifying, useful in delineating issues, dramatic, and at times elevating rhetorically, but it is not to be taken literally. There were no voice recorders or stenographers. Most speeches were extemporaneous.While it may be true that most ancient speeches were extemporaneous, the idea that there were no stenographers is debatable. In my studies on Saint Augustine, I was surprised to find out that there were often "reporters" who followed around the great homilists writing down what they said--in shorthand. See this extract from Thirteen Homilies of Saint Augustine on Saint John XIV (1904) by Hugh Fraser Stewart:
I have trouble faulting O'Connell for this overmuch as he is only reflecting the conventional wisdom among scholars. It is certainly conceivable that Livy's speeches were all fabrications. But I think more caution should be used when making this assumption.
In summary, Ghosts of Cannae is a useful popular history of the Punic Wars. If you have a passing interest in this subject, you will do well to read it.