There are a lot of transformations in this movie. Prince Naveen turns into a frog, then Tiana turns into a frog. Naveen's manservant Lawrence turns into a duplicate of Naveen (but not for long!) Mama Odie's pet snake turns into a dog, a cow, a goat, and some other things. Ray the Cajun firefly, who dies onscreen (unusual for a sympathetic character in a Disney movie!), undergoes apotheosis and turns into a star in the sky next to his beloved Evangeline (awwwwww). Naveen and Tiana turn human again. Naveen turns into the Prince Who Can Mince. Louis the gator doesn't turn human, but he does turn into a jazz musician.
I love how Charlotte, despite being the daughter of the richest man in town, and despite wanting to marry a prince, isn't too self-centered to help her friend Tiana and kiss the frog prince for her (too bad she was *exactly* one second late). And then at the end, she finds out that Prince Naveen has a younger brother. However, he's six years old... so Charlotte says, "Well, I've waited *this* long." Does this mean that when he gets older, she's going to turn into a cougar? :}
One thing that puzzles me is this: when Tiana first kisses Naveen, she turns into a frog. But when Charlotte does so later on, she doesn't. Whycome? It's not explained in the movie. Perhaps Tiana changed because she was meant for Naveen, or something. Perhaps when Charlotte kissed him, the spell was no longer fresh enough to be spread that way. I'unno.
I love this movie. I love everything about it. The animation, the colors, the characters, the songs, the voices, the plot, and of course the furry/TF content! And Tiana and Prince Naveen are both cute as frogs. :}