This book offers great help for me as a german student of an english study programme. The simple structure allows quick finding of every word you look for, the headwords are highlighted in blue colour, synonyms are really(!) ordered by usefulness and the list of synonyms always contains formal and informal versions. There are given antonyms and in some places there are also given boxes with "word links" that explain other useful words belonging to the same subject.
There is a short part in the middle of the book that describes some "Basics of writing good English" where you can check up the common grammar and style rules.
Compared to other Thesaurus` from different publishers I prefer this one because of the good structure and style. I just finished an excellent academic paper with the help of it ;-)