I went on my Level 1 RYA sailing course in April, and didn't get as much practice in as I'd have liked. On the other hand, I like reading up on the theory of things, the "Start Sailing" book was a bit shallow, and I wanted to fill the practice gap. So, I bought this book.
It covers single-handed and double-handed dinghies, at the level of recreational sailing, regatta sailing, and high-performance sailing. I wasn't sure what "regatta sailing" was, and the book never says so explicitly, but it appears to be "trying to sail fast without buying a fancy high-performance boat". As well as the time on the water, it covers rigging and launching. There weren't any topics I was surprised to find present, but it seems to cover most stuff.
Is it any good? I don't know, as I'm not very good! Dinghy sailing is one of those things where you need hands-on experience. Reading from a book is insufficient. There are lots of parts where, when I read it, it either just makes no particular sense to me, or I can pull out the meaning of the sentence, but it's just unrelated to sailing as I've done it at my level. Having said that, little bits are now falling into place as I've been learning on the water, and I can see the book being something that I can come back to as I get better.
While it doesn't really give me next steps in what to do and how to learn, it does still give me an idea of the more advanced skills I know nothing of at the moment - of spinnakers and trapezes, for example. Having said that, I very much doubt I'll ever get into high-performance sailing. :)
Books on practical skills are hard to do well, but it tries hard - there are copious photos and illustrations throughout the book to make things clearer, and they've pulled in some impressive-sounding sailors to demonstrate. Different boats do things a little differently, which makes the book a little trickier to make accessible, but it works around this by using a good number of different boats (even if it occasionally feels like an advert for RS!).
All in all, I think this falls into the category of "books I'd probably recommend, but I don't really know enough about the subject".