**UPDATE** With a combination of self-studying from this book, and group lessons revising all 12 chapters I got 100% in the HSK 1 exam. Message if you want to talk about Mandarin!
Original review:
I waded through this at the rate of just over 1 chapter a week with a teacher from CI.
The course is clear, and concise but gosh can it be a bit dry in places! If you're not up to speed with terms like "nominal predicate" or "adverbial modifier" then the grammar explanations are going to be a bit dense. Heck, even as someone who's comfortable studying languages I found the grammatical explanations sometimes needed a second read, along with careful note-taking.
I also used another website/ app to gain a little more fluency and confidence, and did some extra reading on the side (check my "chinese-learning" shelf if interested).
Fingers crossed that this will have been enough to pass the HSK 1 exam.