The man of numbers
Fibonacci is really a nickname, in his lifetime he was known as Leonardo of Pisa. Devlin tells of his early life, and in particular his time in the North African city of Bugia, where he would have had plenty of experience of Arabic mathematics. He would also have good reason to use it, as he worked in his father's trading business. Most of the book is concerned with Fibonacci's influential book, Liber abbaci, explaining the sorts of practical calculations it described as well as tracing its inflence in the work of later writers.
I thought that Devlin did very well in writing about what could have been a very dry subject. Little is known about Fibonnacci's life, so this is less about the man and more about the books he wrote, but I never felt that the book was getting tedious to read. If you're interested in the history of mathematics, or if you want to find that Fibonacci did more than 1, 1, 2, 3, 5, 8,... then I would recommend that you read this book.