I've read a few books from the "Hacks" series and I'm a big fan. This addition is no different, it's a lot of fun.
As usual it has a collection of well covered items aimed at the beginner, moderate and expert users, but regardless of your experience level there is enough information available to give any of the tips a try. Expert users may even find some gems in the beginners entries!
I was particularly impressed that the book didn't limit itself to just operation on the Blackberry hand-held devices, it also gives tips on integrating it with you desktop and other ways to extend the functionality and get full use out of the device. Possibly of less use is the section covering development for the Blackberry and some of the specifics about the BES and MDS servers, but some of the tips mentioned are of great use to developers and I would recommend the book to them too. Other readers may also appreciate this look under the covers.
"Blackberry Hacks" doesn't stray from the standard "Hacks" formula, so it can be skimmed easily in an afternoon or so, but the projects will keep you busy for a long while, and you'll also have problems holding onto this book due to the people who will be trying to borrow it. This one is a great resource for jump starting your Blackberry usage and getting all you can from the gadget.