19 of 23 people found the following review helpful
Superb intermediate-advanced grammar book,
This review is from: A New Reference Grammar of modern Spanish 3rd Edition (Hrg) (Paperback)
Note, if you are looking for a beginners grammar book, take a look at 'Spanish Grammar' by the same author.
(This review applies to the 3rd  edition). I can only recall a couple of times when I could not find a satisfactory answer in this book, so I'll give it 4.9 out of 5, and I'm fairly pedantic.
One example was the use of the subjunctive after 'no saber si'. In peninsular Spanish this is a complete no-no. However, while watching a Latin American [subtitled] version of the Matrix, I noticed the phrase 'No sé si estés listo para ver lo que quiero mostrarte.' (Morpheus talking to Neo near start of film). As I was confused by this usage I had a look in the book and it does concede that use of the subjunctive varies in Latin America after the construction 'no saber si ...', however it didn't go into any more detail.
The other item is that I would have liked more examples in the modal verbs section to differentiate between phrases such as:
Debí de ir.
Debía haber ido.
Debería haber ido.
Habría debido ir
Hubiera debido ir.
(note it does cover some of these, but not exhaustively)
...and various other forms such as: 'should have', 'would have', 'could have', 'may have' and 'might have'.
But maybe it's just me who found the endless ways modal verbs can be strung together confusing.
Other than these two minor points, I found the book extremely detailed, with thousands of usage examples throughout the book.
This is the only advanced grammar book I have. There is no need for another, as it has answered 99% of all my questions.