I had a background in undergrad Linear Algebra from one of the Strang's book "Introduction to Linear Algebra" before reading this book. Even with that background, I haven't been able to make sense of it, even after watching the accompanying lectures.
The basic problem is Strang loves to introduce an idea without explaining it, perhaps for motivation or to give readers the sneak peek to readers of the wonderful things that await them. In this book, however, he has taken it too far. It's just one idea after another without any explanation, why is the idea useful, and where is it coming from? In the end, I think the struggle to make sense of this book is not worth it.