Outgoing, bubbly, scintillating, no. But that doesn't make it any less of a personality.
Underdeveloped, yes, but that's part of the point of the story- she is so repressed by the expectations of those around her that she can't truly be herself and expose her entire personality.
Mulan has many aspects of her personality. Negatives: Tendency toward pessimism, moodiness, and general negativity, blows off things she doesn't really care about even if they are important to her family, procrastination, erratic behavior. Positives: Courage, loyalty, intelligence, selflessness. I could go on, but I don't want to turn this into an article.

Actually quite the opposite, I think she's one of the most well developed Disney characters.

I know some people say she has an undeveloped personality, or no personality, but she is really well developed as a character!

agree with KataraLover!

NO! I once even wrote a four page description of Mulan's personality and still felt like I had more to say. She is one of the most well developed disney characters.

People who say that take a glance at the movie, think "oh, yet another Renaissance Princess who wants more" and move on, not noticing that Mulan is actually the first of a new generation of Princesses and a very layered character.

I agree with KataraLover and shanyuisboss.

I agree :D I was so worried when a lot of people seemed to say she has plain or no personality.

Swanpride, agree. At surface level, she can appear pretty undeveloped, but she is very multilayered.

Everyone has said it. I love her for her developed personality, not just for her actions. I'm pretty fed up by people who say fans only like Mulan for her actions. It's like me saying fans only like Aurora for her beauty and so on.