Amazon has shipped the new biography to me, but I haven't yet received it. I don't want to comment too specifically without reading the book, but it seems strange that so much of the coverage of the biography has focused on the fact that he was unhappy, as though this was a revelation. Have the people covering the biography actually read the strip, or would they just skip the strips that didn't feature Snoopy? I actually found it more interesting, as discussed in Newsweek, that Schulz seemed to cultivate his depression, nursing imagined childhood slights. Perhaps he needed to feel like the tortured artist, as discussed in the New York Times (love the artwork that accompanies that article), or felt he needed a more tragic back story to lend gravitas to his art, in a field not generally taken seriously.
As far as Schulz's family's complaints about the biography, I would not question their perception of their own father, but I haven't heard anything substantial to cause me to question the accuracy of the biography. Schulz's son complains to Editor & Publisher that 28 pages are spent on Schulz's affair, claiming that to be excessive. 28 pages in a 650+ page book devoted to the affair that destroyed his first marriage certainly sounds reasonable to me. He also specifically claims that the author mentions Jeannie Schulz's trips without Sparky, but doesn't mention when he would travel with his wife; it seems to me a similar complaint could be directed to the family's own Charles Schulz museum, which portrays him as a creature of habit loath to travel any further than the Warm Puppy Cafe a block from his home. Again, my opinion will have more weight, I suppose, once I've actually read the book, but the portrait I'm getting from the reviews doesn't seem too terribly different from what I carried away from my trip to the museum. If anything, he's more well-rounded and human.
And kudos to the Wall Street Journal for getting Bill Waterson of Calvin and Hobbes fame to review the new biography.