I've just finished the sixth book. Throughout the series, I've admired the setting and characters, and the way Paver weaves in her research, enhancing the story rather than making it seem as if she's throwing in everything she knows just so it doesn't go to waste. I've certainly read nothing else like it.
On the slightly negative side, I've found the series less interesting as it goes on. I think this might be because the setting gets a bit repetitive, though i don't see how she could have got round this except by making the series shorter. I also think her writing style changed during the series, though since I don't have the early ones (I borrowed them from the library) I can't check this. It seems to me that her style has become more choppy, less beautiful, and for me, less involving. And though I initially enjoyed the sections from Wolf's point of view, I found that his "language" and thoughts became too "human" as the series went on. For example (and this might seem picky) she's obviously decided that Wolf should awareness of the present tense only, ie no past and no future. This is good, as there are some South American Indian tribes that also have only a "now" awareness. But then she has Wolf "talking" about the "now that was before he went to sleep" as opposed to the "now that is here", which is bringing in the concept of time by the back-door. Wolf and Torak also end up speaking in concepts which I think are just too advanced for even an intelligent animal.
I don't read much YA fiction, so maybe that's being over-critical for the genre; it's just that I think she started the series with a tighter control of her material than she ended it. But again, I think it's a wonderful and unique attempt to portray a culture from the past of our own world, and though I would argue that to some extent these are too much modern people in disguise (for a real attempt at a Neolithic consciousness, try the first story in Alan Moore's "The Voice of the Fire") she is to be commended for it.