Hearts in Atlantis is a collection of five stories, interconnected by characters and events. The first story, "Low Men in Yellow Coats" is the most "King-like" of the group--is is simultaneously nostalgic and creepy, a combination of the wonder of childhood and the darkness that comes with the loss of innocence. King's descriptions are as whimsical and interesting as ever, although the plot would lose something for anyone who hasn't read the "Gunslinger" novels.
The other four stories continue forward from 1960, watching a cast of characters weave in and out of the action, peripheral perhaps in one story, main characters in the next. The events span the course of 40 years, and the structure sometimes reminds me of IT, in that the characters are still being effected by barely-remembered events that happened in their childhoods.
On the whole I enjoyed the book, though it was not exactly what I expected. I would say it most closely resembles Different Seasons, in that the stories contained within run the gamut from extremely good to somewhat clunky and dull. I think in some places King was overreaching in order to fit the stories together. I wouldn't necessarily recommend it to someone who prefers his or her books very plot driven, but it might be good for a person who enjoys reading for its own sake.