If you're going to discuss vices in the novel, it'd probably be more relevant to discuss them in the context of the white settlers or even in the racism of Señora Moreno.
All that aside, let's now look at the virtues of Ramona. One virtue of hers could be following her heart. Even though Señora Moreno doesn't want her to marry Alessandro, Ramona does so anyway. We might applaud Ramona for not putting her true feelings beneath her feelings for Señora Moreno. We might want to admire Ramona for following her heart.
Another virtue of Ramona seems to be her ability to tolerate suffering. A lot of bad things happen to Ramona and her family. Her husband's land is seized by white settlers. Her daughter dies because a white doctor refuses to make a trip to her homestead. Her own husband is shot dead by a white settler.
Yet Ramona doesn't give up. She doesn't despair. In the end, she finds more love with Felipe and has more children.
Although, not to undercut everything we just said, perhaps there's something suspicious about how Ramona keeps on going. Her ability to survive such suffering has a way of making the suffering seem less appalling.