I read The Clan of the Cave Bear series when I was very young. At the time, I loved it, so perhaps that nostalgic feeling prompted me to want to read Shaman, even though I can't say if if I'd still appreciate Clan today. Perhaps it's not fair to compare my experiences reading the two, but I just didn't feel that same sense of wonder while reading Shaman. The Ice Age world that was described felt like it could have been any prehistoric setting, and the characters seemed plucked from modern times.
Loon, the young protagonist, is in training to be a shaman. It might have been interesting if this was pursued more in depth, but instead, we're privy to Loon's constant thoughts of how to go about getting laid for the first time. Perhaps the point was to demonstrate that boys will be boys, no matter what the time period, but it didn't make for interesting reading. When Loon finally does have sex, I think I was more relieved than he was, because I was ready for some form of a plot to develop.
Robinson occasionally departs from Loon's story to write from the viewpoints of animals, including a wildcat and a wolverine. I didn't understand the purpose of this, but it was quite a bit more interesting than Loon's story.