I'm a big fan of the "Visual QuickStart" series of books, which is why I bought this JQuery version to get me started. My experience in this series is that the books do what they say (getting you started quickly!) and are structured so you can work from front to back cover and then use it as a reference book later on. This version is no different, however out of all the books in this series that I own, this is the only one that I found a little irritating at times. It's not detrimental to the content of the book but the thing that was irritating is that each example started with "1. Use a text editor (such as Microsoft WordPad) to create your Web page....". It's only a small thing but why on earth they felt it was necessary to put this on EVERY page is a mystery to me. Sceptics may be inclined to think it was necessary to pad out the pages as it's quite a thin book...
That aside, the book is great if you want to get started with JQuery very quickly. The examples are sensible examples that cover, at least initially, scenarios that you may want to use in a real world project (the section on ajax is particularly good). I did find that I quickly outgrew this book though - but in a way that reflects how well the book works. I still refer back to it but mainly for a quick look at syntax but nothing much else. If it's anything more complex then it's easier to find the answers by googling it.
If you want a quick start in JQuery, then this does what it says so go with this. If you want a monster reference tomb, then go elsewhere (but if you want that for JQuery then you've probably missed the point).
PS. This book doesn't cover Javascript - a lot of people forget that JQuery is something extra to javascript so don't buy this book thinking it'll cover basic javascript as well 'cos it doesn't.