I've not yet read the book so my review, unlike some here, won't be compared to the series. That said, it's an interesting watch in that it's not your typical time travel tale. There are a couple plot holes, but not to the extent that it completely ruins the viewing experience. My biggest issue is that I have a low tolerance for stupidity and some of decisions the characters made throughout the series is downright stupid. They tend to act more on emotion than common sense. While I can excuse some instances of this, it happens too frequently for my liking. Due to this, I feel the series falls within a 6-7 rating. I'll go with the latter in hopes we see less of this in season 2.
