Princess and the Frog is Disney's 49th animated feature, and the first release done in 2D in 5 years. When John Lasetter was named Creative Director at Disney, he immediately reopened the hand drawn animation department, and Princess and the Frog was the studio's return to this media. And it did so in the best way possible.
Going back not only to traditional animation, but musicals and princess tales, the studio brought back a bunch of big animation names that had worked at the studio on the classics.
First of all, the directing duo John Musker and Ron Clements (Little Mermaid, Aladdin, Hercules). They where there when Disney started it renaissance in the late 80's, and they where back again in 2009 for the studio's comeback.
But in the animation department, there were some amazing artists that were in charge of the main characters. Andreas Deja (Scar, Jaffar, Hercules) was the lead animator of Mama Odie, Eric Goldberg (The Genie, Phil) was in charge of Louis the Alligator, Bruce Smith (Kerchak, Pacha) was Dr. Facilier's supervising animator.
Something really great about this movie is that the artists gave themselves the freedom of creating scenes with many styles, so sometimes the animation is really cartoony and exaggerated, sometimes it's more traditional and theres even a great sequence that is super graphic.
All in all, Princess and the Frog is a pretty good film. Great characters, cool villain, nice songs and pretty story.