It has been retitled "To Be Or Not To Be Intimidated?: That Is The Question" due to people thinking it was actually about intimidating other people, rather than standing up to certain types of business intimidation.
It's a mostly autobiographical account of a real estate broker, and how he learned to stand up for himself against a series of different sorts of intimidating business types. There's nothing revelatory in any of this: go in prepared, have a fallback plan, don't buckle under to crazy demands. There is some interesting stuff about real estate brokering in there, which I found interesting, but which can easily distract from what the author is actually trying to discuss.
I read Trump's first book "The Art of the Deal" right after, and I think Trump's book does a better job of doing the same thing with much more interesting stories. First of all, Trump's arena is New York City real estate, which is more dramatic than Missouri real estate. Second, Trump talks about the actual personalities and organizations he dealt with, rather than the cutesy pseudonyms that the Intimidation author uses and the generic locales he describes. Third, Trump, for all his faults, comes off as a real guy with real ways (good or bad) of dealing with business problems, where the Intimidation author is mostly creating a hammed-up and semi-ficitional account of his modest deals.
Bottom line: "Winning Through Intimidation" is ok if you get it from the library, and you enjoy watered-down business parables. "Art of the Deal" is much better if you care about how someone who did some pretty spectacular things describes how he did them (which may or may not be wholly accurate).