Shaman is the coming-of-age story of Loon, a young orphaned Shaman-in-training in a paleolithic European hunter-gatherer tribe. Compared to Kim Stanley Robinson's other stories (which tend to concern themselves with rather large-scale events), it's a small story: It deals with a few years in the life of one person, who lives in a small tribe and can probably count all the people he knows on his hands and feet.
It starts well, with Loon setting out for his Wander — a rite of passage in which he has to survive alone in the wilderness for half a month before being accepted back into his tribe. The pace is strong, and we get a distinct impression of just how grim and unforgiving Loon's world is. We also get an insight into his rather strange psychology: He doesn't really differentiate much between humans and other animals (for instance, he refers to female lions as "lion women", has sexual fantasies involving animals, and regards bears and Neanderthals as lost cousin tribes). He doesn't understand dreams, and believes that he is literally experiencing the strange spirit wanderings of his dreaming mind. During his Wander, he hunts prey, makes ﬁre, outwits Neanderthal marauders and defends himself against bears and lions. He is 12 years old at the time.
Unfortunately, the moment he gets back to his tribe, the story switches pace and becomes almost insufferably dull. He meets a girl, they marry, she gets kidnapped, he attempts a rescue mission, some friends come after him — all of this could make for a ﬁne "minor epic", but for whatever reason, it is all written with a tone and pacing more reminiscent of an uninteresting travelogue. I found it very difficult to care about Loon after the story of his Wander. The supporting characters, with few exceptions, aren't much better: The two tribal elders (Thorn the shaman and Heather the medicine woman) spend most of their time on page engaged in petty squabbles with each other (mostly involving Thorn calling Heather names, and Heather pissing on Thorn's belongings).
The language is frustrating. It's a confusing jumble of modern English and invented tribal terms. Some animals are called by modern names, others have weird invented ones. One character breaks the tone by lapsing into Italian; exclaiming "Mamma mia!".
Although Loon was the main viewpoint character, there were occasional sequences from other POVs — including a few sequences with animal viewpoint characters, notably a small cat (showing us the early stages of feline self-domestication) and a wolverine. These were definite bright points amid an otherwise boring trudge. The character I found most emotionally engaging was a middle-aged Neanderthal outcast with a respiratory illness and a vocabulary consisting of three words (but with superhuman animal imitation abilities). In fact, the speculation about Neanderthal nature was what I liked best.
This is by far the worst I have ever read by Robinson, and this annoys me since I know he can do better. The Mars trilogy was also dull in places, but it more than made up for its occasionally plodding pace by virtue of the setting and the sheer scale of the story. Galileo's Dream and (especially) The Years of Rice and Salt were anything but dull. I know he can do better, and I wanted to like this story (prehistoric science ﬁction generally being an under-used genre). Unfortunately, I couldn't bring myself to care much about the main characters, the language was frustrating and the plot was boring.
Probably best to steer clear.