The new edition of the Oxford American Writer's Thesaurus is superior for several reasons...several of which were left out of the editorial review listed above.
1. I noticed the listing of the words have been updated. The listing of words are now printed in a slightly bolder typeface - making it easier to pick out the meaning.
2. The word headings themselves are slightly larger...again making it simpler to locate definitions on the page.
3. The page layout seems to be cleaner. When you open up any page...you'll quickly notice how much nicer the structured plan is for showing words.
There is one more caveat I'd like to mention. I believe this new version, although labeled "Second Edition", should be considered a revision to the first one and not realistically a new printing. I say this because the jacket description mentions the same number of words are incorporated, namely the listing of 300,000 synonyms. There is no mention of "new" synonyms added to this "Second" printing. Otherwise the editors of this edition would have mentioned the addition of newer synonyms added to this edition. Remember, The Synonym Finder, another good resource, has a much higher listing of synonyms than the Oxford American Writer's Thesaurus...about 1.2 million.
Overall, the Second Edition to the Oxford American Writer's Thesaurus is a much cleaner, easier version to use.