I'm a sucker for most anything King writes, and this is billed as a companion volume to  On Writing.  Even so, it's not illuminating for much in the craft of writing.  And while most everything has been culled from earlier sources, there are several essays and talks here which are rare or new for me. My favorite reads from the work are "On Becoming a Brand Name," his reflection on fame, and "Horror Writing," a novella-length examination of several great horror novels (originally published in Danse Macabre.

More, these are essays and talks from 30+ years ago now, so there are no real revelations and some of the opinions haven't sustained themselves as King's career matured and his experiences shifted. So reader of this won't find much writing advice, they won't find especially new insights into King's behind-the-scenes thinking beyond the essays I named), and they won't find enough good fiction writing to merit the time spent with them--definitely old-school adventure-gore King on that front. 

What you will find? King's homey honesty, his occasional spit-takes on politics and other writers, and a fairly comfortable nostalgia for those early works. For completists and fans, this is unpleasantly relaxing.

For everyone else, you would do better to pick up his excellent On Writing for real craft advice, Danse Macabre for the essays on the publishing world and other writers, and just about any collection of short stories for a better selection of his gifted horror-fun.