One thing is certain, Gabaldon knows how to write romance! The graphically intense love scenes require some acclimation at first but the author's fantastic descriptions pull the reader right in. There are times when the scenes are so vivid and steamy, I felt I was watching more than I was reading. Because of that and the sheer frequency of those scenes, it would be easy to assign it to the genre of gothic romance, but Gabaldon's well-layered period plot and intricate web of characters puts it, in my library anyway, decidedly in historical fiction.
Some early parts of the story seem less than plausible. Despite her primitive-like experiences as an army nurse on the front lines of WW2, Claire adjusts more quickly to the rough and tumultuous way of life in the 18th c. than seems likely. Also, the comfort level that Claire and Jamie share so early on seems dubious as well, given the circumstances.
One of the most enjoyable and thought-provoking aspects of the novel is the idea of time travel as it links generations from past to present. Who hasn't ever wondered what it would be like to live among their own ancestors or other people they've learned about from history? It is, of course, the rock upon what poor Claire's fate rests, quite literally.
The novel has a bit of everything, including action, suspense and mystery. I highly recommend and very much looking forward to reading (and watching!) the rest of the series.