This book is a fun, fast read but as, other commenters have said, the best word to describe it would probably be “cute”.
The plot is set into an alternate-history regency with magic, and is pretty much a fast-paced action romp with simple but relatable characters.
The most distracting issues is that, because of its macguffin nature, one of the main plot points (the main character disguises herself as a man, and could be disgraced if discovered) never really amounts to much of a credible threat, since everyone she meets who can see through her glamour is basically OK with it, is willing to keep her secret, and/or subtly (or not so subtly) encourages it.
The villain, too, could have been given a bit more of a backstory and motivation, as she is basically little more than a cardboard figure necessary to set the plot in motion.
Apart from that, it’s a nice if not wholly original story, and a good way to spend an afternoon.