This looks on the surface like exactly the book I need but a quick look at the amazon reviews shows some flaws, no answers to the exercises seems a bit annoying. I’d also really like an eBook that is formatted rather than a PDF because I read on a phone.

Saying that, I really would like to be better at math so might end up trying anyway.

"This is the ebook edition, a full-color pdf containing the complete contents of the book (the physical book is black and white). Due to the heavy use of mathematical typesetting, there is no plan for a ebook-reader-specific format (mobi, epub). This ebook is a simple pdf download."

https://gumroad.com/l/pim-book

That used to annoy me too but Foxit PDF reader app makes it far more pleasurable an experience. It's not like flipping a page but it's as good as reading a PDF on desktop.

Anybody give this a quick skim and can offer any insight?

Personally I found it quite useful, although I was already familiar with several topics, it was interesting to read the author's perspective. Answers to exercises would be great, but even without them I found the content satisfying and useful enough.

Look interesting!