Heinlein is one of my perennial re-reads, in the "I know some of his writing has huge flaws but I still love his books" category--along with Dornford Yates and Frances Hodgson Burnett. I have everything he wrote and recently went on a Heinlein juvenile kick, but after reading this collection of letters and miscellanea for only the second time, I'm going to get rid of it. There are a few interesting insights, but mostly his letters are dull and Ginny's additions are not well-written (the grammar is fine, but there's no felicity to the sentences, and the sequence and emphasis seem strange). Most revelatory to me was that Heinlein's method of work was to write until he could hear the characters talking, and then he would just let them unfold the tale. This partially explains to me why his later books are so terrible: the characters tend to all sound the same, exactly like him, so of course they have no new places to take him. That's not entirely true--Job: A Comedy of Justice was something of a departure--but it does explain The Number of the Beast, in which what is really a good story is bogged down by the pill-ish, wooden quartet of Bob/Ginny clones, of whose company one quickly becomes heartily sick.