This was okay. It had some things of use, though it depends on what point in your journey of dealing with this issue that you're at. It begins with giving the characteristics of perfectionists and types of perfectionists and trying to convince wavering perfectionists why they should seek treatment for being perfectionists (basically along the lines of: "So, if perfectionism was working so well for you, why are you reading this book, then? Something feels wrong, doesn't it? And if it doesn't, go on your merry way then." You can almost see her saying that in therapy a thousand times over in her career). So if you already know you are a perfectionist and want to change it, there's a decently sized portion of this book that you might be able to skip. If not, she's pretty convincing when you see it in black and white and reading those parts might help you.
There's also some chapters that seem shunted in from what seems to be her main research focus, how families pass down their trauma not only to the first generation, but to the grandchildren and great-greatchildren as well, if the problem is not addressed. Unsurprisingly, a lot of traumatized families and parents try to cope with their issues with hardline perfectionism, and learned that in childhood- and then proceed to mess up their own kids with crazy expectations and not appearing very human. Which is interesting and might help explain the roots of your perfectionism to you if you happen to fall into this category, but if you don't, I can see how you might find that part unhelpful.
What *was* I think the most widely helpful bits of it were the parts where she asks you to make lists of your values and what you would like your life to look like, picking from a list of things she's provided, and then examine how your life matches up with that. She doesn't just give the "good" options she wants you to pick, too- if you pick "I want peace more than anything", she mentions that maybe you want to keep your perfectionism then, because you won't get that with systems that require you to face problems and deal with them frequently. It's a pretty honest inquiry into what you're willing to put up with and what you honestly, really, are motivated to change. I also thought the clear, deep familiarity of the anecdotes she chose and the very specific characteristics she listed showed a long expertise with the issue that inspired confidence.
So this one's okay, I don't regret the time I spent on it, wrote down some quotes from it. But I would overall say that I recommend Brene Brown's book on perfectionism over this one-The Gifts of Imperfection or Rising Strong, which is about vulnerability and getting comfortable with the next step after perfectionism.