While the beginning is a bit shaky, the two lead characters of the story, Claire and Camden, really come into their own once the action sets in, and they play off each other in humorous ways despite the many dangers that they encounter. They feel like real teenage friends; this is probably one of the few books I've read with young adult leads who gush and crush about boys (and their impromptu guardian Hanfei) without it turning into a gigantic plot tumor. Furthermore, their differences and disagreements never completely derail the plot, as a lesser book might have been moved to do. Instead, it emphasizes their strengths and different abilities when addressing tense situations.
Speaking of strengths, it's clear that author has keen attention to detail. From food to modern security measures, Smith adds a layer of realism to this fantastic romp that makes it stand out from other adventure thrillers. Considering this is a book that involves escaping from a sinking pirate submarine fairly early on, that's a pretty remarkable literary feat. While there were a few areas that did feel borderline creepy, especially the handful of scenes where underwear plays prominent importance, it didn't detract much from the story as a whole.
What keeps the story from being perfect is that it ends rather abruptly. Technically, yes, the main plot was resolved. However, the ending leaves open a lot of loose threads, and the last chapter feels extremely rushed in turn. There's not enough time for the main characters to let the major eleventh hour plot twists sink in, and the conclusion is outright told to the reader in a couple of sentences rather than shown properly. The story could have benefited immensely from another chapter or an epilogue to wrap things up.