Griffiths' three outstanding undergraduate physics texts are the poster children for well written, clearly laid out, expertly organized physics text books. Very few physics texts that I've used have accomplished what his have.
His particle physics, electrodynamics, and quantum mechanics books were critical in my early and middle education and development in these subjects. This book, the electrodynamics text, was my first exposure to Griffiths. The book expects very little prior experience with electrodynamics, and builds a comprehensive curriculum almost from scratch. Unlike other notable electrodynamics text books, particularly David Jackson's underwhelming but somewhat useful reference-book-disguised-as-a-textbook, this book gives you everything you need to solve its problem set. And it provides an extensive and interesting problem set that spans a wide range of difficulty.
Because they're undergraduate texts, Griffiths' books don't go as in depth as some other books on similar subjects, but given their breadth their depth is surprising. Even more importantly, the clarity and cogency with which his books are written makes them far more useful than other books geared toward the same level.
When I was in graduate school my Ph.D. advisor said Griffiths' books sucked, and he let me borrow an old EM book he said was superior. I used this book for a little while in my grad level EM class, and found it underwhelming and convoluted and ultimately kind of useless. Even though Jackson's Classical Electrodynamics was the official text for that course, I found Griffiths' book to still be much more useful and instructive. This has proved true of his other books as well.