This book is not for everyone. Suchman makes connections between AI, HCI and the sociological areas of ethnomethodology and conversation analysis (EM/CA) - connections that have been very visible and influential in subsequent HCI and CSCW research. If you don't have any background in these sociological areas, it will take some work to read it.
That said, I think this book is reasonably accessible, and certainly more so than has been suggested by some reviewers. Suchman was writing to counter a prevalent mindset in the AI community of the time. Basically, Chapters 2 and 3 set up a technical and philosophical strawman (human action as the execution of plans), Chapters 4 and 5 provide an explanation of some necessary theoretical background, and the rest is an analysis of interaction in the context of these theories that serves to knock down the strawman. It's fairly hard to have a more clear and logical organization than that. There's no part of that organization that could be left out and still have the book make sense.
Furthermore, by comparison, the theoretical parts of this book should be easier for the uninitiated to read than are Garfinkel's writings on ethnomethodology (or most CA writings by almost anyone). They may or may not do justice to those ideas, but that's a separate question. And for someone with any background at all in these areas (though as suggested by other reviewers, this does not include a huge number of people), this book should be a very straightforward read.
The bottom line for me is that this book (like Paul Dourish's "Where the Action Is") is an interdisciplinary gem that has the potential to change how you think about how people approach technology. There aren't that many books for which that can be said.
