Yes, I use that workbook you mention. The exercises are identical to the ones on the ICW site. In addition, the book does provide some commentary on the Bluebook rules and some examples, but you really learn by doing. I think the book sells for something like $25, so if you have the money to blow, go ahead. But, the exercises are exactly the same as the ones on the website, so if you can learn how to use the Bluebook (which is a real pain, I know) then I'm not sure it's worth it. Having said that, the workbook does have a nice concise checklist of the rules' requirements at the end of each section to help figure out which Rule you need to use.
See if your bookstore has a copy of the workbook and look through it. I think you'll find that it's somewhat helpful but I can't be your judge as to whether or not it's worth your investment.