Of the three SECOND FOUNDATION TRILOGY novels, this is, by far, the worst of the three. Asimov's writing style is self-described as "direct and spare," (which Benford notes in the book's Afterward)...Benford's is almost the complete opposite.
This book took me 2 to 3 times longer to read than any other Foundation Novel because of all the EXCESSIVE descriptions, and emotional backgrounds of the two SIMS (since I did not enjoy the writing style, I read it across many short-term intervals, instead of "devouring" it in fewer, longer intervals...like other Foundation novels). Luckily, Greg Bear and David Brin do MUCH better jobs at duplicating Asimov's writing style in the second and third novels of this trilogy.
If it wasn't for the fact that both "Foundation and Chaos" and "Foundation's Triumph" reference aspects of this book, I would recommend skipping it entirely. However, to fully understand the nature of the SIMS, you really should read it first.
To his credit, Benford did do a fair amount of research into Joan of Arc and Voltaire for this novel (i.e. The SIMS). Unfortunately, it seems he felt it necessary to include as much of that research as he could into this book. In my opinion, this book would have been improved had he left out a great number of emotional speculations in regards to the SIMS, and simply let the reader come to their own conclusions.