Personally Vasari was a man of upright character, free from vanity, and always ready to appreciate the works of others: in spite of the narrow and meretricious taste of his time, he expresses a warm admiration of the works of such men as Cimabue [1240-1302] and Giotto [1267-1337], which is very remarkable. As an art historian of his country he must always occupy the highest rank. His great work was first published in 1550, and afterwards partly rewritten and enlarged in 1568, bearing the title Vite de' più eccellenti architetti, pittori e scultori italiani (The Lives of the Most Eminent Italian Architects, Painters and Sculptors). It was dedicated to Cosimo de Medici [1519-1574], and was printed at Florence by the Giunti; it is a small quarto illustrated with many good woodcut portraits. This editio princeps of the complete work is usually bound in three volumes, and also contains a very valuable treatise on the technical methods employed in all branches of the arts, entitled Le Tre Arti del disengao, cio architettura, pittura, e scultura. His biographies are written in a very pleasant style, interspersed with amusing stories. With a few exceptions Vasari's judgment is acute and unbiased. And though modern criticism, with all the new materials opened up by research, has done valuable work in upsetting a good many of his traditional accounts and attributions, the result is a tendency very often to underestimate Vasari's accuracy and to multiply hypotheses of a rather speculative character. The work in any case remains a classic, however it may be supplemented by the more critical research of modern days.
Vasari gives a sketch of his own biography at the end of his Vite, and adds further details about himself and his family in his lives of Lazzaro Vasari [1399-1468] and Francesco Salviati [1510-1563]. The best edition of Vasari's works is that published at Florence by [Gaetano] Milanesi (1878-1882), which embodies the valuable notes in the earlier edition by Le Monnier (1846); another, by Venturi, was begun in 1896. The Lives has been translated into French, German and English (by Mrs Foster, London, 1850).
Source: Entry on the artist in the 1911 Edition Encyclopedia; see also entries in the Wikipedia and the Catholic Encyclopedia.