Shirkey is a great lecturer - he's genuinely pretty funny, he conveys the material in an interesting and lively manner, and his explanations of the content are clear and concise. I took comprehensive notes and found that almost all the time the material we were asked to discuss in exams or on essays was covered thoroughly in lecture. It's worth coming to class for that reason alone. He also interacts with the class somewhat regularly and given that this class seems to attract a lot of veterans, students who don't have that background can gain a lot from listening to the discussions he has with vets about their experiences and how they relate to the course material.
For students interested in security studies and strategy, I would recommend taking this course with the forewarning that the syllabus is not that organized. The class deals with, among other topics, the theoretical basis of strategy, military doctrine, civil-military relations, state-building, the relationship between economic development and war, arms races, the revolution in military affairs, air power, alliances, military intervention, civil wars, future wars, air power, air power, and air power. Shirkey really, really loves air power. If there is sufficient demand for a seminar on the subject I imagine he could talk about it for literally days at a time if asked.
I guess the course is hypothetically exploring "how and why states and non-state actors use violent and non-violent strategies in international politics," according to the syllabus. In reality, I think it's a kind of disparate overview of topics that relate to international security and it isn't obvious why some topics are discussed and others aren't. It's not hugely centered on the U.S. perspective - Shirkey has an impressive command of history and the examples he cites are usually good for understanding the concept at hand and drawn from diverse periods in world history. But I'm not that certain that there is any strong theoretical impulse driving the course or that I have a better understanding of how states make decisions about their security at the philosophical level, although he and the readings do a good job of distilling the basis of decision-making processes at the micro-level of why, say, a state might abandon an alliance partner or launch a targeted air strike at a nuclear facility.
So: expect animated, interesting lectures and a detailed overview of each topic on the syllabus, and there isn't really an excuse for not knowing individual definitions on the exam as long as you come to class and take good notes. Do not expect that you'll be diving deep into military strategy or theory or reading tons of Clausewitz. From what I understand, Richard Betts's War, Peace and Grand Strategy is the best option for that. I'm hoping to take that in the fall and perhaps this course will serve as good preparatory material for that class. I did think the class was still worthwhile - probably the best political science course I've taken two years in as a major, not that that's necessarily saying all that much - and I think it's especially important to consider taking this class if you're really focusing on IR here.