All the best continental philosophy* books display the best and worst things about continental philosophy: they introduce a profoundly useful concept and make a number of interesting but lesser points about the world in general while they do it. They also needlessly confuse the concept itself, display far too much irrelevant learning (of the "I was reading book x while I was writing book y, therefore book x and y are somehow connected" variety), and make statements that are so over-the-top and ridiculous that any sane reader will only retain her sanity by keeping in mind Adorno's marvelously self-referential claim that all real thought is exaggeration.
According to this implausible statement of mine, Homo Sacer is among the best continental philosophy books. Agamben introduces a very useful and interesting concept by thinking about a)sovereignty, particularly as discussed by Schmitt; b) the figure of homo sacer and the much discussed 'ambiguity of the sacred'; and c) Foucault's concept of biopower. The concept is 'bare life,' which is what the figure of homo sacer is meant to have, what sovereignty rules over, and what Foucault (ait Agamben) was really trying to get at.
This should all be plain sailing, really: the sovereign, Agamben suggests, doesn't so much decide on the exception as decide on the boundaries of legality. The sovereign has the power to turn someone (or some group) into homines sacres, or 'bandits,' or, more making the idea a bit clearer, outlaws. Homo sacer, the outlaw, is both no longer subject to the law- but also no longer protected by it. He can kill you if he wants, but you can kill him without having any legal problem. So the sovereign and the outlaw both stand at the boundaries of human law, civilization etc... When you're in this position, though, you don't really have a full 'life' as such. You aren't a citizen, you aren't a subject- now you're bare life. I doubt it's very nice. This brings with it some interesting points about Heidegger (Dasein as a kind of benign bare life, which is no longer subject to power structures or politics or whatever), anthropological investigations of the sacred and a bunch of other issues in which you might be interested.
Now for the bad stuff:
i) this interesting concept does not allow you to make wildly exaggerated claims like 'economic development turns the entire population of the Third World into bare life,' or 'concentration camps signal the political space of modernity.' Regardless of whether some people are treated as bare life, the vast majority of us remain citizens.
ii) Aristotle's discussion of potentiality in book theta of the Metaphysics has nothing to do with sovereignty, no, nothing at all, and no matter how much fancy footwork you do you will not make them have any relevance to each other. Pindar might have something to do with it, but in a very uninteresting way. Kafka probably has something interesting to say about it, but Agamben doesn't tell us what. Benjamin certainly does, but you could only explain what in a freestanding book length essay on him. All this means that about two thirds of part one of this book are gratuitous and quite irritating. This is a side-effect of the argument-by-outlandish-example method, which also takes up too much space in part three: 'scientists sometimes turn people into lab rats' adds nothing to the concept of bare life.
iii) And finally, I actually have a complaint of substance: despite all the talk of bodies and biopolitics and what-not, Agamben's work is the worst kind of obfuscating idealism. I say this as someone who doesn't mind a little idealism every now and then. But saying 'the Romans conceived of homo sacer in this way... and now we're all homines sacres' leaves out a couple of pretty important *millenia,* through which one probably can't track the figure of homo sacer. What possible effect could this fascinating but arcane legal dispute have today? How is it that such ideas have some immediate impact on people who have never had a politically theoretical idea in their lives?
Agamben could answer, say, 'that's not what I mean; it's not that these ideas have actual worldly effects in the present. It's just a way to think about our world.' That would be okay.
*But*, I'm pretty sure that's not what's going on. He routinely says things like "only a politics that will have learned to take the fundamental biopolitical fracture of the West into account will be able to... put an end to the civil war that divides the peoples and cities of the earth," p 180. I suppose we could dedicate the next twenty years to re-thinking the relation between politics and bare life and sovereignty and so on. We could try to get an absolutely true political theory that steps beyond all of western history and metaphysics, since *only* then will injustice cease. But I'd like to think it isn't *only* when you have a perfect political theory that you can take steps to stop the environmental, political, economic, social and cultural havoc that we seem intent on wreaking.
*yes, I am aware that continental/analytic is a silly distinction, but it holds in this case.