I've got that book. Bought it from a bike shop a few years back. IMO, it is a good book, and can be quite informative. However, the one drawback to this book is that it does not tend to be as comprehensive on older bicycle repairs (like adjusting the old-style U shaped brakes. that pretty much every bike used to come with), but focuses on relatively newer stuff. If you get it, then you can always supplement missing information (if you have got older parts that the book doesn't cover) with stuff printed off from Sheldon Brown's website.

When I was assembling bikes on my own at Wal*Mart, I started keeping this book on my workbench as a reference work to try further improving the quality of my assembly work (and thus learned some finer points of bicycle repair). I also have a smaller book that I picked up at a Garage sale called "Bicycle Repair" (who'd have thunk it?) by Bicycling Magazine that has a bit of useful information on older bikes and some older methods of doing things. At one point, I also had a binder of material printed out from Sheldon Browns website that I took to work with me. So, if you can get stuff printed from Sheldon's site on the cheap, that would also be a good option.

But certainly, I doubt you will find that book to be useless. I have really enjoyed it. If the shipping is descent, $21 isn't bad, since mine is listed at $24 US (I paid something like $30-35 Canadian for it).