Most other dictionary-format thesauri (Roget’s II, for instance) simply won’t give you what you want on the first try. If, for instance, you want a more decorous word for “smelly” you’re brusquely told to “see MALODOROUS”. This means that most of the words you are likely to be looking up require a time-wasting two step process: first find the word you want to replace, then find the main entry for that concept. By the time you’ve finished flipping back and forth through the pages you’ve forgotten what it is your looking for.
The Webster’s version is a thousand times more convenient. If you look up a specific word you’re guaranteed to find about a dozen or so of the most common synonyms right there (funky, stinky, rank, etc.). This first entry is probably all you’ll need and it constitutes the main time-saving benefit of this edition. But there’s more. The real verbomaniacs among us get referred to the main entry of the concept. Here you’ll find the mother lode of words, often numbering into the dozens and ranging from the most commonplace to the ridiculously obscure (e.g. mephitic, olid, or stenchful). You’ll also find related terms (vile, rotten, pestilential), contrasting terms (deoderized, fresh, clean), and antonyms (fragrent, sweet) all in the same place, just as you would in Roget’s conceptually arranged International edition. Like I said, most writers are sure to find what they need on the first try.
The only other thesaurus that approaches this one is the Random House Collegiate, but I don’t think that one has definitions; this one does. I’m also pretty sure this one has more words than Random House, Roget’s 21st Century, or any other.
(I’m glad the guy below got to know thesaurus.)