Also read Robert J. Sawyer's book, Hominids. This novel won the Hugo for best science fiction novel recently. Don't be fooled. The Hugo's are voted on by anyone who wants to be a member of a world science fiction convention. Essentially the science fiction writing public. And they follow Sturgeon's Law: 90% of everything is crap. They certainly did with this book. It's crap.
Here's why. Nothing happens. Here's the basic plot. A portal opens between a world wherein
Neanderthals became the dominant human species and our world. Ponter Boddit a physicist, is sucked through. We don't really know what to do with him. Meanwhile, back on the other side, Ponter's partner is prosecuted for the murder of Ponter because he's now missing. Sounds exciting, right? Wrong.
This book is Sawyer's attempt to create the perfect society. In the book, all the characters ever do is sit around and discuss the differences between human society which is all fucked up, and Neanderthal society, where everything is perfect. It's an exercise in world-building. Numerous sf writers have done that, and sometimes it's interesting. This time it's not. It's not because the world is too perfect. Almost nothing ever goes wrong in Neanderthal society. Boring. The method of revealing the alternate world is boring. Sitting around talking all the time? Sure, that's realistic. That's pretty much how most people learn about new things. But a book should be interesting. It also has the standard crap about how we're likely to mistreat the first Neanderthal/alien/person not like us as soon as we see him. Possibly true. But again, something that's already been explored way too many times.
In the end, it seems like Sawyer has little new to say. There's no real new take on any issue in the book. Sf is great for exploring issues without indicting people. (Ask me if you want an explanation of that.) And it has a sucky plot and characters. Without one or the other, the book just falls flat.