Nassim Taleb wrote this review (5 stars) for Sornette's book Why Stock Markets Crash:
The author aside from the problem of crashes presents an insightful exposition of tipping points. I don't know why his approach makes it clearer and deeper than those of Watts and Barabasi --is it due to his using financial markets as a base? or his being an expert at fat-tailed dynamics? His work builds on the "abyssus abyssum invocat" (panic begets panics) and the dynamics of compounding disequilibria. In addition the notion of "CRITICAL POINT" is made very clear. Honestly I don't care for the idea of crashes; the same concepts can apply to sudden and unexpected euphorias. I learned more from this book than any other on disequilibrium.