Actually, I don't recall the source material really defining and developing her especially well. She does develop throughout the story a little though, in both the original books and in the Disney movie. I don't think Disney did anything wrong with her as such, but perhaps there was some room for improvement that they didn't take advantage of.

I feel like she's the most well-developed character from the Classic Walt Disney era. She was someone that wanted everything to be nonsense but didn't realize how bad that can be when she wants things to make sense or to show off how knowledgeable she is when logic has no place in Wonderland. She learned that there is a time and place for everything, which is why a place like Wonderland where everything is nonsense like she originally wanted to live in as "a world of her own" is better to visit from time to time but not to permanently stay in because being sensible and logical is important as well. Plus she has a three-dimensional personality, so she's the most well-rounded of all the character from Walt's era.