One of the best and most complete textbooks I've ever come across for Classical Mechanics. It's outrageous to even think of using Goldstein's book, when you have a golden standard like this one for Advanced Undergraduate and Graduate courses.
What this book does best is that it provides the reader with excellent geometrical insight, which helps develop a real intuition for the subject and also spot what's missing. This helps while dealing with theories like Relativity and Non Linearity, to which this textbook also provides excellent introductions.