This is an intriguing piece of historical fiction. The two main characters are both strong women, although in different ways. Christi Phillips switches between seventeenth century Venice and present day with ease, and her writing style makes everything very easy to read. If you have an interest in Venetian history, or just like historical fiction or heroines in general, this book may suit you.
I would have liked a little more suspense. Parts were supposed to be suspenseful, but they didn't really seem that way to me. I guess that if this book has any failing, it is the fact that parts of it just seem handed to us as more of a recount than a dramatic narrative. The most exciting part, to me, was actually near the end when Claire was almost arrested--the parts with Alessandra in the Doge's prison at the hands of Silvia was not nearly as fun. I don't think that Phillips gave us enough of Alessandra's character with which to empathize with her and her love for Antonio. After her debut as a courtesan, indeed, Alessandra becomes more distant from the reader. Claire, on the other hand, becomes more accessible. Parts of the book are rather predictable, and others come as surprises (I did not foresee Andrea Kent actually being Andrew Kent, nor did I foresee their collaboration).
The Rosetti Letter is a solid, enjoyable novel. I wouldn't rush out to buy it, but if you don't have anything in particular to read next, you could do far worse.