This book asks many interesting questions about the history and future of media. Examples include:
1. Why did the sight-only medium of silent movies get wiped out completely by "talkies" while the sound-only medium of radio survived television?
2. The most powerful leaders of the past 150 years were Churchill, Roosevelt, Hitler, and Stalin. Was this power due to the nature of radio as a medium, and the fact that radio flowered when they were prominent?
3. Is centralized authority in media necessary (because people need "gatekeepers" to filter information for them) or a result of the economics of mass media (the high cost of sending radio signals compared to the low cost of receiving them)?
4. Does information want to be free?
Levinson's answers are not always as good as his questions. His explanation for the survival of radio (as a medium you can use while doing something else) was persuasive. His view that the leaders of WWII drew their power from radio was less compelling.
Levinson's view of the decentralization effects of computers is valid. The opposite view, which is widely held, is a serious misconception.
Otherwise, when discussing the future, Levinson is disappointing. He says less than what can be found in other work that predates his book. The issue of the future of paper is discussed better in some of George Gilder's articles in Forbes ASAP, going back to 1994. The issue of how to pay for information is discussed better in Brad Cox's work on what he calls "superdistribution." The issue of the status of artificial life is discussed better in Steven Levy's book on that subject.
If I were teaching a course on the Internet, I would include "The Soft Edge" as background reading early in the course. It would help students start to think about the evolution of media.