Instruct: Classify the given review as either positive or negative.
Query: Excellent reference book

I've been playing for about 20 years. I wanted to learn some of the harder concepts that I either skipped over or never understood. This book will take you to the next level if you put in the time. You'll need to practice at least 20 minutes per day and this is not a book for beginners. I have bought several other books and this is the best one. The other critiques are true, but this is still a great book. Pick it up and your playing will improve as long as you spend time with each section.