This is the second time I've read this book. The first was a copy I borrowed a few years ago, and now I've purchased one for my own library. I try to collect good books I really loved reading, and "War an peace" easily falls into this category.
It is an epic novel in the truest sense of "epic". Stretching over a period of several decades, it masterfully describes the history of Russia from the end of the 18th century and into the first third of the 1800s. At more than 1600 pages, it is definitely one of the longest novels out there, but unlike many much shorter books, its length is well justified. I can barely count on the fingers of one hand the amount of times I felt some section is too long. Although Tolstoy is very thorough, his writing is easily readable and the pages just fly.
The books focuses on two main topics. One is the Russian-French wars of 1805 and 1812. Tolstoy describes the wars, and in particular the battles of Austerlitz (1805) and Borodino (1812) in vivid detail and apparently very accurately from a historic point of view. The characters of Napoleon and Kutuzov (the Russian army leader) take active part in the narration, with the lesser leaders (Bagration, de Tolli, Davoux) also getting enough attention to build a complete and interesting story. Specific events of the war are highlighted with the participation of the book's main characters, like Andrey Bolkonsky, Nikolay Rostov and Pierre Bezoukhov.
The other is the high Russian society of that time. The book provides a very interesting and in-depth glimpse into this unusual society by today's standards, somewhat modeled after, and thus similar to, other European societies (French, British, etc.). Tolstoy also presents the life in rural Russia a little, and the interrelations between the rich and the serfs, although he doesn't spend on this topic nearly as much as in Anna Karenina.
The characters in the book are various and present the different ideas Tolstoy tries to infuse into his narration. They are all, without exception, extremely believable and well developed. I can't think of many authors who know how to present and develop their characters as well as Tolstoy.
Additionally, the book presents plenty of interesting philosophical and scientific ("science of history") ideas. The chief one is undoubtedly the question "What causes and shapes historical events?". Contrary to the popular dogma that historical events are the result of actions of single notable persons (such as Napoleon or king Alexander), Tolstoy believes that such persons don't really cause events, but rather can only affect them in some ways once they are already in existence. He claims that what really changes history is the amalgam of human actions, built from thousands, nay, millions of small decisions, desires and ambitions of the people. A historical version of chaos theory.
Well, this review can be arbitrarily long, and I have to wrap up at some point. I just want to address one important issue - the book's name. In Russian, the book's name is "Voina i mir", which may mean "War and peace" but may also mean "War and society", since "peace" and "society" are homonyms in Russian. There are differences of opinion as to which Tolstoy actually meant when he authored the book, as you can read here or more at length here (Russian). Personally, I firmly believe that the "War and society" translation is more correct. It is very obvious that Tolstoy places a lot of emphasis on society in the book. Pierre compares his experiences in the society with his war adventures to form philosophical opinions. The same for Andrey. I can barely see any mention of peace in its "non-war" sense in the book.