I program since 1982, from Texas Instruments pocket calculators to J2EE Java. I have to admit my skills improved pretty slowly and I wish books like these would have been available years ago. And I wish, too, I would have had a bigger interest and insight did every craft can be improved - yes - gasp! - Even my own programming style. Your code might work pretty well, but this book will challenge you to "expect more", and "do more". And, yes, it can be done.
If you're good at programming you probably will be familiar with a number of the ideas presented, and you'll find confirmation for practices did you felt were "the right thing to do". And Then There will be some more tips to help you to improve your style.
The book summarizes frequent realworld observations and resonates with my own experiences slogging through code messed up beyond recognition by programmers who are just "getting the job done". Understanding, Maintaining, and Extending existing code Should not be as painful as it is way to oft. The book gives concrete, usable advice on how to do it better.
I would make Both books a "must read" for Programmers I hire - If They understand and like what is presented, They Could not have a better start on better programming.