This was a well-done, well-edited fun, interesting story until the very end. The character of Paula was constructed solidly and was believable. The character of Catherine, who came into the future when Paula went 100 years into the past, was less well-defined and, I thought, lacked the depth that the author skillfully provided for Paula. This was a case where the author appeared to favor the character of Paula over Catherine, and it was evident. I actually found myself preferring Catherine.
It also appeared that Ms. Toon wanted to deal with the life of the person in the past, Paula, more than she wanted to deal with the person in the present, Catherine. She did that well, but I would have liked a more in-depth picture of Catherine's reaction to present-day San Diego.
The ending for Paula was satisfying and not exactly what I expected (that was good). The ending for Catherine was brutally abrupt. Totally unsatisfying. It was almost as though the author just didn't want to or know how to deal with Catherine in the end. That's the reason I gave book 3 stars instead of 4.
This was, otherwise, a good book. This new author shows real talent. At the end, though, I got the feeling that she just wanted to finish it. 10 - 20% more text at the end would have rounded it out much better.