(Physicist here.) Looked at TOC, then skimmed some chapters. The special relativity part of the book is about as deep and denser than most undergraduate introductions, with less motivations and intuitive discussions. The general relativity part is dense by necessity (after all 95% of it is differential geometry, no way around it), and this book apart from being way more condensed isn’t in any way diluted.

It’s a compact book of essentials for mathematically minded people*. It’s not a shallower-than-textbooks accessible introduction one step up from pop science.

* If you only ever took some linear algebra and calculus for engineering students, this probably doesn’t describe you.