When a book arrives from a publisher, it is accompanied by an information sheet/ press release. The bright-eyed and bushy tailed view of these is that they provide useful information for the editor or review writer. (The cynical view is that they provide nice words about the book that some lazy hacks will just reproduce, in classic press release journalism. But I'm not cynical.)
I must confess, I rarely give these more than a quick glance before reading the book. Yes, I do read every book I review, almost always cover to cover, with the exception of books where I decide that my review would be so nasty that I really shouldn't do it - and usually the publisher agrees this is a good move. I don't want the publicists' words to influence my thinking about books - I want to come to it with the same information that a casual purchaser would have.
There are really only two significant things I check - the email address of the publicist, almost inevitably down the bottom, so I can let them know the review has gone live, and the publication date, because I don't want to review a book months before publication, and sometimes I get sent them ridiculously early. (When a book is very early, it is usually a bound proof, rather than a real book, which I don't like. The only possible excuse for this is if the publisher wants me to write a nice couple of lines to go on the back of the book, otherwise they are the devil's spawn.)
When I do glance at the publication date, just occasionally I will see something like this:
|From a real book information sheet|
(Publisher's name hidden to conceal the guilty)
The idea of an embargo is that readers get all the publicity at about the time the book launches, so it's fresh in people's minds, and I can see that's a good thing. But on the other hand, perhaps it's good to build up the awareness a bit earlier? Perhaps this date doesn't fit well with my publishing schedule?
It was the particular case illustrated above that gave me a bit of a pain in the backside - I wrote the review on Saturday intending to go live with it this weekend... and now I've got to sit on it for a couple of weeks. (The review. Not my backside. Well, not the whole two weeks.)
So... I can see why they do it. It sort of makes sense to get a flurry of activity and awareness around the time the book goes on sale (though if that's really what's wanted, why not embargo it until publication date?). But I honestly don't know if it works in a marketing sense. I'd be interested to hear if anyone has done research on this. And when most books are listed on Amazon months for pre-order months before they are available, I do wonder if the embargo is a concept from a different era.