As Joshua Hammer wrote in The New York Times,
Prose rebuts the charge that Frank’s diary was a “found object” — the inconsequential scribblings of an adolescent whose death elevated it far beyond its value as a work of literature. In fact, Frank intended her writings to reach as wide an audience as possible, inspired by a radio address given by a Dutch minister of education in exile who was determined, once the war was over, to establish an archive of accounts of life under the Nazis. In the spring of 1944, Frank, then 15, rewrote and amended earlier entries, making scenes more vivid, deepening characters, shifting seamlessly, as Prose puts it, “from meditation to action, from narration and reflection to dialogue and dramatized scene.” .... She makes a persuasive argument for Anne Frank’s literary genius.exhibit at the Anne Frank Museum in Amsterdam takes you through the moveable decoy bookcase to a tour of all the rooms of the "secret annex" in which Miep Gies protected Anne, her family, and their friends—eight people in total—for two years. In this video, Anne's descriptions take you through the hiding place.
I must confess to not having read the diary (yet). Comments from those who have would be welcome!