The character of Tiana could have been a flat "Cinderella" type character who works all day hoping for a man to save her. Instead, she is a wonderfully modern princess—a passionate, intelligent, creative woman who is concerned with fulfilling her dreams through work and learns that having a career doesn't mean she has to miss out on having love and a family. Charlotte could have become a flat "Ugly Stepsister" type who vies for Naveen's affections and cares more about money than people. Instead, while she is ditzy and cares about finding true love, Charlotte also cares about friendship, and offers to help Naveen and Tiana when the time comes. Naveen could have been an empty "Prince Charming" who the viewer never really gets to see, let alone know. Instead, we watch his slow transformation from a narcissistic playboy to a caring self-sacrificing man.
I have been to New Orleans 3 times, and loved the music and scenery the film provided. Viewers see the rich Creoles, those who live at the heart of the city, the more indigent African American and Caucasian families living outside of the city, and the Cajun culture of the bayou. Each scene was painstakingly created, and the effort shows. The film could not have been set anywhere else. The setting is integral to the film.
As an adult, I loved this movie. The only thing that parents might object to their children seeing are the scenes involving voodoo. For a young child, the Shadow Man could be quite scary, particularly a scene in a grave yard where he tries to capture the Frog Prince. People with strong religious views might also be offended by the scenes with Mama Odie. However, I would urge modern viewers to think of these scenes in terms of the fairytale construct—they are meant to be seen in terms like the Evil Queen of Snow White, who also used magic, or like Ursula of the Little Mermaid, who was also trying to take someone's soul. Similarly, this film doesn't present the Shadow Man and Mama Odie in terms of religion, but in terms of magic. They could very easily have been an Evil Stepfather and a Fairy Godmother.
Overall, I thought that The Princess and the Frog was a fantastic film. The songs were jazzy and had shades of Gershwin, the scenery was beautiful and varied, the characters were well thought out, and the plot had enough twists and turns to keep me interested. I haven't enjoyed an animated film so much since Beauty and the Beast came out in 1991.