Worked through this book over winter break with a PhD friend of mine at another university. The first few units were mostly review of familiar concepts in academic writing for myself as a native English speaker, but towards the middle and the end there were plenty of tiny bits of knowledge that I'd never thought of before. Also, speaking with my friend about the slight differences we had in our answers on some tasks really made the discussion more robust.
While yes, this book was helpful in terms of self-reflection at times, it is especially helpful to work through in a group or with others. Probably it would have been even more beneficial if that group consisted of people from more than one discipline (though it was good to have someone else in the same field to see if you agreed for your field). Overall, I recommend it to new graduate students or those who want to polish up some of their own writing.