Let's start with the novel, since that's how I did it. (Deliberately; I can't read the novel after the show or movie. Once I've watched it, that's pretty much a commitment not to read the book; see Little Big Lies.)
Shadow is in jail for three years on a small time offense, but he'll be out in just a couple of weeks, and he can't wait to get back to his wife Laura. When she dies days before his relief, his whole world is pretty much empty--until, on the way to her funeral, he meets Mr. Wednesday, an unorthodox con man who offers Shadow a job.
Mr. Wednesday is charming and insistent, and Shadow is at loose ends, so they begin to cross America together, enlisting other old-timers like Mr. Wednesday in the impending war. Apparently, the old gods and the new can't get along. Shadow is his driver and assistant, sounding board and sidekick, and he begins to learn about the much, much weirder side of the world.
So, the thing that Neil Gaiman does so well is to place the fantastical and portentous beside the mundane and everyday. It's what Stephen King does, only where King goes straight to grandiosity and horror, Gaiman lingers in the land of wonder--Gaiman's gods are as mundane, in their own ways, as the human world in which they coexist. But the power of this book is in the long drives through small towns with their high school athletes' achievements on the welcome signs, the stops for roadside chili and pie (not bad, but not the best chili in the state, however it was advertised), and the neighbors you get to know when you realize that you are unprepared for a Colorado (I think?) winter and need some help finding the long underwear store.
Even Shadow is an everyman--the loss of his wife has him drifting across the top of life, not really digging into it (or maybe he's just like that?)--but he is not prepared for the supernatural that starts to go down. He takes it in stride like someone on a mild tranquilizer would, in that he realizes that this is impossible nonsense, but also that it's happening and that rolling with it is really the only viable option.
I think that's what I loved best about the book--how it really captured the feel of a diner or an apartment full of old people or a public park in a way that allowed you to follow the story when it drifted into the "backstage" experiences that involve the moon and the world tree.
But (and here we're going to be switching over to episode 1 of the Starz series) this is just where the TV adaptation drops the ball, I think. Or no, that implies that it tried something and failed; the TV adaptation is playing a totally different game--I was expecting some kind of ball game, but I got pro wrestling instead.
The show could not possibly be more glossy. It uses slow motion and shifting frame capture rates to create hi-res visuals. There are multiple scenes in which a curtain of blood just washes across the screen, looking like cherry Kool-Aid. The best chili in the state is served at a bar shaped like the inside of an alligator's mouth. It's a really cool visual--but it goes straight to surreal. The experience of a mundane world that touches a stranger one is missing, because the entire world is strange and hyperfocused. Instead of seeing the banal in the gods, we are seeing the otherworldly everywhere we turn.
I might be the only person who was not impressed by this. I'm somewhat less of a sucker for high art on TV than a lot of people--I like a good looking show, but not when the style gets in the way of the substance--characterization, emotion, story--which I think was happening here.
But I will say, I did really love the book.