I'm working on my PhD in Geography. This was a required text for a first-year graduate seminar on "History and Theory of Geography". This book gives a biographical sketch of numerous recent luminaires in Geography. The book is easy to read because it's broken down into nice nuggets of information about a specific Geographer and makes mention of how their work relates to other Geographers also in the book. Granted, it's not comprehensive, but it does give a good foundation in the theories behind modern Geography.
If you are into Geography (with a capital-G) and not just geography, buy this book. Even if you don't read it right away, it'll find a comfortable spot on your bookshelf.