I borrowed it once from a friend and after reading a few chapters felt that it was mostly a chapter of smoke and mirrors surrounded by something that was already known and could be explained far more succinctly. The Amazon reviews showed that others felt the same.

Wolfram is brilliant, but I'd rather read a book from him that showed him solving all sorts of neat problems.

Bought the book some years ago, but never really got through it. Keeping it handy though in case I need to knock out a burglar. Thing is massive, shipping was half the cost ;)

And the same reason I returned it to Barnes & Noble within two days.