How is Juliet characterized in act 1, scene 5?

In this scene in which Romeo and Juliet first meet, Juliet is presented as a girl who is transitioning to adulthood. She is innocent and inexperienced but, at her mother's prompting, open to falling in love and to entering the world of adult, married people.
According to Romeo, she is captivatingly beautiful: "Oh, she doth teach the torches to burn bright!" She is also intelligent and playful. When the lovers first speak to each other, they create a sonnet in which each completes each others thought. While Romeo has long been living in an imagined world of Petrarchan sonnets, Juliet seems to be able to extemporize these ideas naturally.
That sonnet indulges in incredibly romantic imagery, comparing love to religious devotion. Both innocent and seductive, it captures the beauty of these lovers emerging passion. And like the dance in which the couple seems to be engaged, the verbal wit involves an equal give and take from both lovers. Most remarkable in this case is Juliet's ability to match Romeo in his conceit and to both pursue her own desires without succumbing simply to his. This quality will mark their relationship. Despite Romeo's playful seduction, Juliet responds, "Then have my lips the sin that they have took," seemingly inviting another kiss. She also gently teases him, "You kiss by the book."
As the party ends, she urges the Nurse to discover the name of the man she has kissed. We see her dissembling so as to not arouse suspicion from the Nurse as Juliet asks the name of several other men before seeking out Romeo's identity. Given the closeness the Nurse and Juliet seem to have, we might assume that this caution could be the first time Juliet has not been open with the Nurse, perhaps the first time she feels she has an adult experience or thought worthy of keeping private. She ends the scene telling a small lie about what she has just exclaimed:

A rhyme I learned even now
Of one I danced withal.

In short, in this scene we can find the trajectory of a charming young girl into a charming young woman, caused by Juliet's sudden awakening into romantic passion.