Yeah he is jazz-focused but the book is still quite good. And yes, it helps tremendously is you already know your basic music theory. Beginners will get stuck if they rush the excercises. I would also suggest supplementing his book iwth a good music theory book or aid, heck the 'net has so many free sites such as www.teoria.com. His book on scales and modes for jazz is supposed to be just as great. I got mine for $10!!