This book is very much a product of the age it was written in. Jung was describing a weird, ground breaking concept and took exceptional pains to demonstrate that a) synchroncity was real and b) he wasn't barking mad. Unfortunately the pains he took to persuade a sceptical scientific audience, for it was them he particularly wanted to convince, don't always make for an interesting read.
At least a quarter of this book gets bogged down in the tedious maths surrounding his research data. Its not remotely interesting to most people and I found myself skipping large chunks of it. On the other hand a lot of the rest of the book is very thought provoking indeed.
Many people use the word synchronicity, often incorrectly and clearly few of them have read this book. They really should. I'm glad I did.