DNF - read to the 43% mark. I started this series with this book.
It was okay to the start the series in the second book, because the character had her memory wiped from the actions in the first book. The first part of the story was interesting as the quantum reality starts slipping for our perky heroine, bringing nightmares, waking translocations to other worlds, and the ability to speak perfect French in time to pass the language oral examine in her high school.
I couldn't handle it when the actual meat of the story began. A planet where everyone is a genius, getting doctorates, to the point of silliness. Also I had a hard disbelief that everyone in the world, once shifted south, still overlaps so well with everyone Laney knows on her world. How in the world is everyone still that white? It's a typical YA, one level of change without really thinking about all the impact on society. Simplistic but unrealistic. And Laney's and Noah's interactions are headache inducing with her constantly going off on her own, or delaying things, or him knowing she doesn't know things and but still acting like she does. I couldn't deal with it.
So DNF just shy of half-way.