Obviously as a White Dude (TM), I'm set up for failure when criticizing a book about how white people can't handle honest discussion about race and racism. About 80% of the book is entirely unobjectionable (to me), but there are bits that rankle.
First up, I'm not sure what use the book is. Part of DiAngelo's job is moderating racial sensitivity training seminars at the behest of corporations or other groups. A fair amount of the book really seems to be her complaining about her job. "And then there was this white person behaving like this at my seminar. Wypipo, amirite?"
The book does do a good job of exploring and describing the various defense mechanisms that white people use when confronted with unpleasant truths. But is this news to anyone? I guess I was hoping more for strategies for dealing with those defenses when encountered in the world (or inside). But there's precious little about solutions, just a clinical description of the symptoms of the disease. OK, this is perhaps valuable, but I expect it is old news for anyone likely to pick up the book and read it, and the people who would learn a thing or two are not likely to pick it up.
Next up, nomenclature. Now, I understand the use of "racism" to mean something that might be more fully described as "systemic racism" or "institutional racism". I'm cool with that, but it seems like it would save time in her workshops if she used those longer terms, since it seems like she spends a great deal of time fighting against the 'common' understanding of racism. Especially since the actual situations that come up in her seminars are a lot more like common racism than systemic racism. She's not being brought in to address redlining, but to address people being nasty to Suzi in the breakroom. So there's some equivocation on the use of "racism" in the book.
Similarly, she blithely asserts that American culture is a culture of white supremacy, that most schools are segregated, and "For example, although we are taught that women were granted suffrage in 1920, we ignore the fact that it was white women who received full access or that it was white men who granted it. Not until the 1960s, through the Voting Rights Act, were all women—regardless of race—granted full access to suffrage."
I think a lot of these blanket statements need some asterisks. I mean groups who identify as "white supremacists" mean something different than the systemic racism that already exists in our culture. To call them both "white supremacy" is again equivocation (or at least cause for confusion). The 2018 elections showed that there are still some limits to voting access. If we can only celebrate when "full access" has been granted, then we still cannot celebrate women's suffrage. By no means do I want to minimize the disenfranchisement of blacks in the South -- quite the opposite -- but this hairsplitting seems absurd.