H&K's book contains what linguists of the minimalist faith regard as seminal work in argument structure, in trying to explain why there are so few thematic roles by appealing to possible structures based on spec-comp relations. Their theory was explicitly endorsed by Chomsky in the 90s, and most minimalists revere C so much they will take H&K's work as axiomatic. Thankfully, you do not need to follow minimalist theory to read this book, it is written very clearly so that linguists of other faiths can grasp the concepts.
Outside the cult, linguists with a few grey hairs will recognize the ideas as amazingly similar to an earlier period of "Generative Semantics", when people were analyzing KILL as CAUSE-TO-DIE, and some will question why Fodor (1970) or Chomsky do not launch their invectives again. Actually, Fodor does (see Fodor and Lepore 1998) his usual routine, but Chomsky does not, for reasons we do not really know. Also, see Kiparsky 1998 for other sorts of objections concerning P incorporation. Suspiciously, the authors make very few references to the original generative semanticists, or to other lexical decomposition analysis (e.g. Jackendoff, LRH) - as one would expect from good scholarly work - thus this theory stands in isolation. They do not help us understand how to deal with Fodor's valid claims, so we are left with confusion on how to place their theory on comparable terms with others.