'The editorial work behind this project has been immense in scale. Every book that Beckett mentions, every painting, every piece of music is tracked down and accounted for. His movements are traced from week to week. Everyone he alludes to is identified; his principal contacts earn potted biographies. When he writes in a foreign language, we are given both the original and an English translation (save for some French verse that is left untranslated—a puzzling editorial decision). By page count, some two thirds of the volume is given over to scholarly apparatus, principally elucidatory commentary. The standard of the commentary is of the highest.'
J. M. Coetzee has written about the first volume of Samuel Beckett's Letters in the New York Review of Books. A superb piece of writing. You can read the article in full by clicking here. The web journal Ads Without Products has posted its own commentary of the article here.