James Boswell's Life of Samuel Johnson is often called the greatest biography of all-time and may well be. Perhaps such a work can get no higher praise, but it is also highly notable as the first true modern biography - the first really resembling what we think of as biography today. Boswell set new standards for thoroughness, accuracy, and research, greatly expanding the very concept of what a biography could be. He was also very far ahead of his time in anticipating what was later called gonzo journalism - writers inserting themselves into real-life stories; it is of course not done in the same way as later writers, but the concept is similar. Most remarkable of all, though, is that the book is immensely readable, entertaining, and edifying over two hundred years later, which can be said of very few biographies. It is absolutely essential for anyone even remotely interested in Johnson, Boswell, or the late eighteenth century European intellectual circle.
Johnson was perhaps England's best known writer during his last several decades and one of the most famous in the world besides being widely known and renowned for lexicographical and other accomplishments. However, this book's greatness and fame are such that he has long been known primarily via it. Many read it who have read very little or none of him, showing that, unlike nearly all biographies, it has earned a life of its own. There are many reasons for this, not least the fine writing. Even more fundamental is that the book vividly brings an exciting, integral, and profoundly influential era to life. It covers the late Enlightenment when many of the most important people to ever live were prominent. In addition to Johnson, we get first-hand glimpses of such illustrious personages as Adam Smith, Oliver Goldsmith, Pasquale Paoli, David Garrick, and many, many others. Numerous other heavyweights - Voltaire, Jean-Jacques Rousseau, King George III, etc. - are only slightly in the background. We also get contemporaneous accounts of major events like the American Revolution and the lead up to the French Revolution. In short, though ostensibly the biography of one person, the book is as vibrant, lifelike, and memorable an account of a supremely important era as any history book.
Yet Johnson is always the focus, shown literally from birth to death. Anyone interested in him will find a wealth of information about all aspects of his life as well as his thoughts, feelings, influences, intellectual background, and far more. There is also a great deal of information about his work. Unlike nearly all biographers, Boswell actually knew Johnson well; he was his friend for many years and spent several months annually in his company, essentially interviewing him and making voluminous notes of his conversation. This last is indeed the book's heart and by far its most famous element. Johnson was perhaps his era's most famous conversationalist, revered for wit and argument; Boswell heard many hours of his conversation and reports faithfully. His style here was again innovative. Rather than sprinkling isolated quotes anecdotally, he went to great pains to reproduce full conversations, not only describing the setting and others present but even using drama-like name headings for full verisimilitude. We thus not only see what Johnson said but where, how, and usually why he said it. Many world famous Johnson sayings that would otherwise be lost - i.e., "Patriotism is the last refuge of a scoundrel" - are immortalized here, as well as some quotes by others. This alone would make the book of great value.
Much has been made of how Boswell's presence affected this; knowing he would write the biography, or at least thinking it possible, he undoubtedly orchestrated much, drawing Johnson out when he might have otherwise been silent. Much of this would have been done in any case as he clearly admired Johnson and loved his talk, but there is no denying the question's importance. Some have condemned Boswell as a shameless celebrity whore or otherwise questioned his motives and veracity, but nearly everyone will consider this nitpicking, fascinating as the question is. For nearly everyone, it makes the book better - far more personal and engaging than biographies are usually even capable of being. Also, for what it is worth, such things mean the book in many ways tells us nearly as much about Boswell as Johnson, making it a sort of hybrid biography/autobiography.
Boswell understandably focuses on the years he knew Johnson, meaning the book is greatly lopsided in favor of the later years after Johnson became famous and nearly all his major work was done. This will annoy those who want a more balanced overview, especially as Boswell makes short shrift of some important early events. Those wanting a more conventional balance should get one of several later biographies, especially as Boswell makes a few errors and, at least according to later sources, leaves out some highly interesting - if not necessarily essential - facts. He openly admits doing so at the start in order to protect Johnson's reputation, though much of what he says elsewhere is unflattering, but some of it may have been unknown to him. For most, though, this is the only Johnson biography that will ever be needed - and its greatness, influence, and importance are such that it is required for all readers with even the slightest interest in English and European literature and history and the art of biography even if they care little or nothing for Johnson or Boswell.