...if it were possible I would have given 10 stars to this book!
The units are perfectly well organized.
It is really a self-study reference and practice book for intermediates, as mentioned on the front cover.
It not only talks about each subject in general, but also gives very many and very illustrative examples. Whenever appropriate, it compares with other grammatical forms.
One more important thing about this book is that it warns you about what "not to say"... This clears all the doubts in your mind about confusing alternatives.
There is also a section about the differences of American English an British English.
I use this book as a reference. I covers almost all the topics in English Grammar. Whenever I feel I need to repeat some subject, I just find the corresponding unit(s) from the contents. Usually there is no need to read all the previous units in order to be able to understand the "unit" that "you need" to study.
What else can I say!
Special thanks to Raymond Murphy and Cambridge University Press for this wonderful product.