Drake does help make the characters more accessible by including a 35 page biography (in a separate appendix) of the people mentioned in the course of the book. The fact that there are over 150 different people involved who need to be developed in an appendix though shows how this biography can be perplexing.
What I did enjoy was the chronological (almost diary like) fashion in which the events in his life are reveled. This style made each subsequent chapter/year of his life (each chapter for the most part represents a year) something one eagerly awaits to see the new discoveries or controversies it will hold. I especially found the portions dealing with the invention of the telescope and subsequent discoveries in the universe to be exciting. The narrative (by using actual letters, notes, etc.) allows one to feel that they are almost there experiencing the new observations right along side Galileo. The first portion of the book is far more difficult to get through than the middle and later portions which contain the more exciting aspects of Galileo's life.
It is amazing to find out how many of the things in science, which we take as a given today, were first thought of, discovered, or proven by Galileo. Before reading this book, I didn't know that many of the things he is credited with were not known or existing before the 17th century. The book caused me to reflect on what it would have been like to have lived just a few hundred years ago when the general knowledge and technology were at such low levels compared with today.
Reading the letters to and from Galileo make the book worth the price. I especially enjoyed the last portion of one to Galileo in which the author of the letter thanked him for "enlightening cloudy minds". That phrase brought a smile to my face. :-)
Other links of possible interest: Astronomy Picture of the Day -
(very cool) Solar System Simulator
Mysteries of Deep Space
Other links of possible interest:
Astronomy Picture of the Day -