The book has totally fascintated me - from the first word to the last line. The book allows an real inside into the world of mathematicians and their struggle to meet Fermat's challenge. However, while the main theme is Fermat, Simon Singh still mentions other important mathmaticians, starting with the ancient greeks and Pythagoras, working through the centuries and the mathematical genius. However, while outlining some of the big mathematical achievements, Singh still writes plain English and remains understandable. The book is made even better by the proves in the end of it - 'showing the beauty of Maths.
The book is a "must buy" for anyone if an interest in mathematics. You will be fascinated by it for sure!