A New Kind Of Science?

I read much of Stephen Wolfram’s book A New Kind of Science when I borrowed it from someone who received it as a gift but wasn’t particularly interested in the dictionary sized tome.
I can’t claim to have read it from cover to cover, nor did I attempt to code up Java versions of the various cellular automata to see how they all worked. What I did glean from it though left me feeling like I got half of what was promised. What I got from it was that what we perceive as “extreme complexity” can often be produced from a very simple set of rules acting in concert. From this Wolfram hypothesizes that things we see in chemistry, physics, biology, etc. may all be driven by very simple sets of rules. Unfortunately, what he never does, at least as far as I could determine, was work out how you could tell when it is a simple set of rules driving apparent complexity. How can you tell, and how can you discern the rules? Without that information what you’ve got is some interesting mathematical exercises and a whole lot of theories.
Wolfram has just put his book online at the link above so you don’t have to plunk down $45 (or more) to come to your own conclusions about it.