This book covers the first part of Napoleon's return from Elba in 1815,the beginning of "The Hundred Days". This book uses eyewitnesses and participants accounts, and often quote their own words on the events. The same tecnique as the author used in his triology on the Invasion of Russia in 1812.  
This book gave me an insight on the period from Napoleon landed in France until he was safe in Paris, that I have never experienced in other books on the topic. Most books cover this period of "The Hundred Days" rather quickly, so they can get to the main event, The Battle of Waterloo. Here we follow Napoleon from his landing in the south of France all the way to Paris. We are also told how Paris react to news of the landing, and how the statesmen, soldiers and ordinary people reacted on Napoleon's return.  
 
To summarize, I think it is a very good book on an interesting period in history, and I look forward to the next book, covering the rest of "The Hundred Days".