The very first art critic to review Van Gogh's paintings was Albert Aurier (1865-1892), and it happened during Van Gogh's Lifetime. Aurier was a painter himself, as well as an art critic. Aurier was passionate about Symbolism, then an emerging art movement. His review, "Les Isolés: Vincent van Gogh", was published in January 1890, on pages 24-29 of the magazine Mercure de France. This was "a magazine read at the time by everyone with an interest in modern art".1
In it, Aurier aligned Van Gogh's art "with the nascent Symbolist movement and highlight[ed] the originality and intensity of his artistic vision".2
In his review Aurier described Van Gogh as the only painter he knew "who perceives the coloration of things with such intensity, with such a metallic, gem-like quality", his work as intense and feverish, his brushstrokes as fiery, very powerful, his palette as dazzling, and said his technique matched his artistic temperament: vigorous and intense. (Full review, in French.)
Aurier also published a shortened version under the title "Vincent van Gogh" in L’Art Moderne on 19 January 1890.4.
Vincent van Gogh wrote a letter3 to Aurier in February 1890 to thank him for the review. "Thank you very much for your article in the Mercure de France, which greatly surprised me. I like it very much as a work of art in itself, I feel that you create colors with your words; anyway, I rediscover my canvases in your article, but better than they really are — richer, more significant."
Van Gogh then goes on to deprecate himself: "However, I feel ill at ease when I reflect that what you say should be applied to others rather than to me" and right at the end he gives instructions about how Aurier "would do well" to varnish the study he'd sent him.
1. History of the Publication of Van Gogh Letters, Van Gogh Museum, Amsterdam
2. Heilbrunn Timeline of Art History: Vincent van Gogh, Metropolitan Museum of Art
3. Letter to Albert Aurier by Vincent van Gogh, written either 9 or 10 February 1890. Van Gogh Museum, Amsterdam
4. Notes to Letter 845 from Jo van Gogh-Bonger to Vincent van Gogh, 29 January 1890. Van Gogh Museum, Amsterdam