Robert McCrum in The Guardian:
Like some of the greatest titles in this list, James Boswell’s life of Dr Johnson, the most famous biography in the English language, had a protracted, tortuous and tortured gestation. Boswell first advised his friend and mentor of his intention to write his life in 1772, when Johnson was 62, and the would-be biographer 31. He had, however, been making notes and gathering materials for his “presumptuous task” since their first encounter in 1763. After Johnson’s death in 1784, Boswell settled down to organise a “prodigious multiplicity of materials”, a labour that, he admitted after five years of struggle, was costing him acute labour, perplexity and vexation. Moreover, he was being overtaken by rival lives (A potboiling “biographical sketch” by Thomas Tyers had appeared in 1784; Hester Thrale’s Anecdotes of the Late Samuel Johnson in 1786; then A Life of Samuel Johnson by his friend and executor, Sir John Hawkins, came out in 1787). Worse, he was becoming a figure of pity and contempt in Grub Street, the self-appointed biographer who had both missed the bus and simultaneously failed his own life’s mission.
However, when it was published in 1791, Boswell’s Life was soon recognised as a masterpiece, a fitting monument to a great English writer and an extraordinary work of art in its own right. Naturally, there was the usual sniping. During the course of a life in Grub Street, Boswell had acquired many enemies. The main objections to his work fall under three heads: first, as the work of an acolyte, it’s plainly not a conventional biography; second, even by that standard, it fails – Boswell only knew Johnson in the latter half of his life and sometimes took outrageous liberties with his material; third, as an exercise in “life-writing”, it falls short, being scarcely more than a loosely linked string of scenes from a life. To which the obvious riposte is: open the book, forget about the narrow academic critique and read one of the most original works of English prose, as much a mirror to its author as to it subject.