The Essential Stephen King is written by an obsessive fan, and is a ranking of all Stephen King's works from 1 to 100. Has Stephen King really written 100 works? Well, that was my first thought, but if you include, as Spignesi has, short stories, essays, poems and even introductions, then yes he has. Each work is outlined in a synopsis, with a few paragraphs on why it Spignesi and others consider it worthwhile, a quotation from King about the work, a background on what was going on with King while writing it, and a little factoid or two about its characters or links to other works.
I love lists, and am one of those people who happily sits down to watch four hours of "The 100 greatest movies" or similar list shows on TV, so this book was right up my street. I've read most of Stephen King's books, so was able to agree or disagrree with Spignesi's rankings, and I wasn't affected by spoilers. There are alot of spoilers in the book, so if you haven't read much King then I would advise steering clear of this one.
The one area of King's writing that I haven't read quite as much of is his short stories, and that's something I definitely need to put right soon, as the synopses of some of them sound amazing (though I covered up the endings with a piece of paper so I couldn't be tempted to read the ones I didn't know!). This book will have the effect of making you want to re-read every single one of King's books, and I found myself wistfully thinking how nice it would be to work my way through all of them chronologically. But if I did that, there wouldn't be much time left over to read anyone else's books!
The Essential Stephen King is a few years old now, so doesn't list any of King's more recent works, and only lists the first four volumes of the Dark Tower saga. I think it's about time Spignesi got to work on a new edition.