Initially, I did not think it would be possible to read and understand this work; I had read excerpts from it numerous times over the last several years and found it impenetrable. However, after purchasing the book and carefully reading Lingis' Introduction, it was much easier than I had thought. All in all, it took three month's of close and careful reading to complete, spending about one or two hours per day, usually first thing in the morning. I don't think this is the hardest work I read -- I failed miserably and eventually gave up on Deleuze's Difference and Repetition after about 140 pages -- but certainly it was the most profound, and disturbing.
Unlike Totality and Infinity, which dealt in depth with a number of different but related ideas, Otherwise Than Being (OB) is really much narrower in its scope. It deals specifically with subjectivity. Levinas uses an idiosyncratic terminology throughout this work. The word 'essence' in this work does not denote essence in the Aristotelian or the Husserlian sense. For Levinas it means simply 'being'. Another possible point of confusion is the word 'anarchy' which in OB does not have any political connotation; it means simply an-archic, or untimely, beyond time. The word 'interest' (or French, interesse) in OB means an inwardness of essence, the depth of the subject's inwardness in essence, or belongingness to being.
There are some rather extraordinary claims in this work: Most importantly the claim that subjectivity itself is constituted by the exposure to the other in proximity. An even more extraordinary claim is that coherent rational discourse dissimulates transcendence, and "owe[s] its coherence to the State, which violently excludes subversive discourse" (p. 170). The work is extremely unsettling in this regard, for the anarchy of responsibility for the other is not to be confused with some project or intention willingly taken up by the subject. It is a hostage situation that is entirely passive, "an anachronous birth" in me, which I cannot except myself from. Over and over throughout the text this point is belabored: that this is not, not, not to be confused with self-sacrifice or being a do-gooder or asceticism. It is a phenomenological description of how subjectivity is constituted.
Whether one in the end accepts Levinas' claims in this work, or brushes it off as nonsense, one will have to face the question of whether the Otherwise than Being is true. For Levinas, there two (several) truths: there is the beyond essence, and there is essence, just as there are two times, the past that was never present, and the present. This work is profoundly disturbing because it is claimed that there is no escape from the Good beyond being; dismissing the book as nonsense does not exempt you from the anarchy of responsibility.