Great book for people who have never encountered a case interview before. This is the book for all the basics that you can build on. However, be wary of forcing all cases into the 12 frameworks they provided. Most cases don't fit nicely into these packages and the book does not cover Private Equity cases.
If you are prepping for a case interview, I recommend that you pull some examples from the companies website, ask if you can do mock cases with people from their office, and practice, practice, practice. Additionally, you don't need to do 30+ cases to do well in an interview. Instead, you need to spend just as much time reviewing the practice cases you do as you did prepping for and participating in the mock interview. If you want a consulting job in this competitive environment, you'll need to be the top 5% of candidates and can't afford to have a "tough case" during the interview. You'll have to be prepared for anything.