I must say that I was greatly impressed, both by the man's ideas and his presentation of those ideas. He is obviously a man who thinks things thoroughly, spending a great deal of time on building his opinions on sound logical foundations. On top of that, he is a man of principles - he has basic philosophies of life, and does not compromise them for any reason.
I am fascinated by the community-minded aspects of the whole Free Software philosophy. No wonder Steve Ballmer and his lackeys have compared it with communism. Although that's surely a ridiculous and typically simian comparison, it does have a slight grain of truth to it - Free Sofware is about building communities and contributing to society as opposed to making a profit through divisionism and monopoly.
Also, Stallman's analysis of the software patent situation was, as far as I could tell, spot on. If I thought software patents were a bad idea before hearing Stallman lecture on them, I am totally won over now. Broad-ranging software patents on algorithms or some vague ideas are harmful to software development in general. It is the software itself as a whole that has a value, not the various ideas that it uses. Stallman likened the current situation to a 18. century Europe where composers could get patents on general musical ideas, thus stagnating the whole music scene.
Well, Stallman said it all better than I can. Maybe I should just finish with a link to the fine fellow's page.