New Oxford Dictionary for Writers and Editors: The Essential A-Z Guide to the Written Word (Reference)

As a poor punctuator I love this book because it has finally taught me what I should have been doing all along. It is an essential aid to consistency and I feel my work looks more polished as a result of following its guidelines.

Great!

If you like to write accurately, or have often wondered whether laissez-faire takes italics, this is an excellent reference book. It is full of authoritative guidance on fine points of grammar and spelling, eg the difference between Baliol and Balliol, whether "balaclava" takes a capital, or when you can use the word "gotten". The book is nicely produced, a sensible size (not too huge) and makes you feel erudite the minute you pick it up. It's also fun to browse in.

The only drawback is that some points of spelling or grammar I've wanted to check are not in the book. Result: I've found myself using it less than I expected. So, only four stars.