There was a lot about this that made me want to give it a lower rating - over-reliance on the people I don't care about, 20 year time jump, angst, Frank Randall's name, use of rape/attempted rape/sexual blackmail as a plot point (which is used again in the third book), Claire's stupidity regarding Jack Randall etc etc BUT, ultimately, certain things make all of that forgivable. 
 The book opens in 1968 where Claire Randall has returned to Scotland, bringing her 20 year old daughter with her to meet a young historian called Roger. We find out that Claire has returned to Scotland to tell her daughter about her real father, one Jamie Fraser, presumed dead at the battle of Culloden. We then go into a flashback where we resume where we left off in Outlander, and discover that Jamie and Claire are resolved to try and prevent the Jacobite uprising that will decimate the Highlanders. 
 This attempt takes us to Paris and then back to Scotland, and although the Paris section does drag on occasion, it does introduce us to the wonderful Fergus, and for that, I can only appreciate it's inclusion. The story really pics up when we get Jamie and Claire back to Scotland, and amongst all the characters we care about. It makes the slow inevitability of their fate all the more heartbreaking as every decision seems to take them closer to disaster. 
 I think it is fair to say that the success and failure of these books rests solely on Jamie and Claire - their relationship is what holds it all together and it is so much more than just their amazing chemistry. They talk, they fight, they joke, they ask advice, they look after each other, they have a partnership and it is the best thing in the book. It is no coincidence that the least successful parts of the book involve them not being together. 
 Their final scenes together are heartbreaking and wonderful and even if I hadn't loved the whole Scottish segment so much, I would have given this a high rating solely because of this scene. It is that good. 
 Just be warned - this book ends on a cliffhanger, and although it was pretty obvious (there are 7 books in the series, afterall) it is still advised to have the third book good to go.