As far as I know (or can remember), Duma Key is unique among King's novels in that it's written from the first person.  Aside from this peculiar little quirk, the book feels as if it has been assembled from material recycled from The Shining and The Dead Zone.  Which is a pity, because it only serves to remind you how much better those other books were.

King's protagonists have always mirrored his own personal situation.  I'm sure you won't be surprised to learn that Edgar Freemantle is both ridiculously wealthy and recovering from a terrible car accident.  The accident has also altered his temperament, Phineas Gage-style, and his wife has divorced him. Edgar takes refuge in a giant rented mansion on a small private island in Florida.  Is it similar to King's own giant mansion on the Gulf of Mexico in Florida?  I can't say for sure, but I can guess.

Once there, Freemantle begins to paint.  And boy does he! Everything he paints is hailed like the second fricken' coming of Christ.  Sorry if that sounds bitter, but the "he fell to his knees and gasped aloud at the brilliance of Edgar's painting" thing does get tedious.  There isn't even a good reason, plot-wise, why everyone who sees Edgar's paintings should breathlessly worship his talent.  It's puzzling and the art-worshiping scenes are lazy, and what's the use of a protagonist who doesn't have to struggle for his fame?  

Duma Key itself is responsible for Edgar's sudden painting skill, of course.  I couldn't help but think back to the way the Overlook was responsible for Jack's sudden maniacal writing binge.  Jack, too, was convinced of the brilliance of the art he created "under the influence."  Except that eventually we learn that it really wasn't, which rang so true.

Second on the annoying list is a white man named Wireman who had a Hispanic wife, and who now ends every utterance with a Spanish word or phrase.  Lest you think I kid, I just opened the book to a random page and found both "All in good time, muchacho" and "Now you're talking, mi hijo," and I only wish I was exaggerating.

When Wireman isn't actually in a scene, Edgar is name-checking him.  Wireman says this, Wireman says that.  I was pretty sick of good old Wireman by the end of the book, I tell you what. In fact, part of the reason I kept reading was that I was convinced that Wireman would turn out to be a figment of Duma Key's imagination, much like the bartender at the Overlook. (Spoiler: no, he's real, he's just a crappy character.)

Here is Duma Key's problem in a nutshell: just before the final bit starts, just as the story really starts to gain momentum, the protagonist decides to take a nap.  And it's not a significant plot-related nap, either; he's just tired.  When he wakes up, of course, he needs a bit of coffee to get going.  

    "Wireman, will you put on coffee?"  I asked.
    "Do we have time?"
    "We'll have to make time.  There's stuff I need, but what I first need is to wake up."
    
No, you don't need to wake up, except in the sense that the story needs to WAKE UP.  This takes place on page 630 of a 769-page book.  If ever there was a place where the protagonist should take a nap for no good reason, this is not it.

Aside from the big stuff, there were little annoyances as well.  The narrator describes a teenage girl's physical appearance with just the word "ripe."  Not once, not twice, but three times.  Every teenage female the book encounters is described this way, except for a pair of tween girls, which are described as "pretty in a not-quite-there-yet way."  I don't think we're meant to wonder if the protagonist is a skeevy pedophile, but there you have it.  "Ripe."  

You know, the more I think about it, the less I like Duma Key.  There are several moments of surprise and terror, but nothing like what you encounter in King's better stories.  The final hundred pages are moderately gripping, but aren't nearly strong enough to compensate for the story having chased its tail for the first six hundred.