I can't think of anything I disagree with in this well-written book... and yet I found it unsatisfying.
It offers 21 observations about successful leadership, each of which is entirely reasonable. But as a guide to becoming a better leader, I felt there were just too many laws. In the end it felt like an exhortation to be the perfect hero-leader, which I didn't find helpful.
For me, the book doesn't penetrate deep enough to the heart of how to become a better leader. It's one thing to point out 21 "laws" - basically a set of truths around leadership and some ideal characteristics of leaders - but it's quite another to identify their psychological roots and suggest a way to work on them. What I missed here was a deeper, more fundamental view of how to become a successful leader; something that would help an aspiring leader learn how to embody the 21 laws, not just know about them intellectually.
Gary Hamel's criticism of the book "The Profit Zone" springs to mind. The authors of TPZ describe 22 "profit zones" - 22 distinct ways of earning a profit margin. Hamel wrote of the authors, "They know a strategy when they see one - Look! Twenty two profit zones! - but they don't know where new strategies come from. They don't have a theory of strategy creation..." I feel The 21 Laws of Leadership has the same problem.
So '21 Laws' is okay, but even though they are mostly 20 years older, I prefer John Adair's books with their simpler action-centred leadership model. If you want a more modern view, try James Scouller's "The Three Levels of Leadership," which goes deeper into the moral and psychological roots of leadership while managing to say compact. Or you could try Steve Radcliffe's "Leadership Plain and Simple."