The book also is too much of an overview--it makes a good introduction but a poor reference text. It is also very poorly indexed, which can make it hard to find things. The exercises are also poor--many new concepts are introduced in the exercises at the end of the chapters.
The writing is actually pretty good, for the most part. I think that the stuff that is explained in the book is explained well in most places, and the author does a very good job of tieing things together and bringing in historical background and significance of the topics being discussed.
I lastly might add that the name is very misleading--the geometries described in this book were mostly discovered over 100 years ago--there is nothing drastically "modern" about them.
Overall, this book was not prepared for being published--it needs a new edition to correct errors and tie up loose ends."