The introduction of comfortable, casual, clothes to the usually formally Princesses results in Cinderella saying “so this is love” followed by a clear sigh of joy.
The line is actually the name of the song that Cinderella sings upon dancing with Prince Charming in the original animated classic.
The Disney Princess sequence is probably the best in the movie from a pure humor standpoint.
One that might have been less obvious, however, comes from Cinderella after the assembled Princesses have remarked on Vanellope’s odd clothing.