I liked this one a lot more than the first book in this series, The Letter. A lot of that is that I liked Jacob a lot more then I liked William (since I hated him, that doesn't necessarily mean much). I also really liked Mary Rose dressing up as a boy and working on the rail road. I expected Jacob's reaction to be worse then it was, but he was just surprised that he hadn't realized it. Her getting hurt and everyone finding out she's really female was very Mulan. Not sure if that was intentional or if it just worked out that way. It was a good way for Jacob to find out, after all.
I hadn't expected Mary Rose to go to Paris, but go she did. It could have gotten her killed but I guess Jacob had to be the hero somehow.