I remember being very excited when this book came out and eager to pick it up, but somehow it wasn't quite what I expected. The most "useful" part, for me, was the theorization of asemic writing in chapter 1, which served as a historiography of the genre. The next chapters looked at three historical precursors/founding figures to asemic writing (Henri Michaux, Roland Barthes, Cy Twombly), eco-asemic writing and a broader discussion of what gives meaning to written "marks" like language, and three contemporary creators of asemic writing who produced book-length projects in the genre (Michael Jacobson, Rosaire Appel, Christopher Skinner). The final chapter discusses the idea of reading asemic writing and the correspondence between linguistic form and meaning.
I personally found chapters 1 and 3 (on eco-asemic writing) to be the most exciting and potentially useful as future teaching material because of the way Schwenger probes some of the bigger questions. Chapters 2 and 4 might be more of interest for people looking to get deeper into the subject and who enjoy close analyses of case studies, which I tend to struggle more with unless I deliberately seek said case studies out. Will be keeping this book in mind for the future, I anticipate I will return to it again, hopefully with more time and focus.