She's alright. Probably my favorite of the princesses from Mulan 2. She's better than Aurora and especially Merida but that's it.

Definetely in my bottom two. No, not because she is a sequel character. I actually find Mulan II an interesting sequel. Not a qualitied sequel but a somewhat interesting one.
I can't decide if I dislike her or Merida more. I believe that freedom is more worthy to sacrifice duty for than Yao(not, because he is not handsome but because he is a very unpleasant character whose only redeeming quality to me is him not caring about Mulan's gender which is still slightly devalued by the fact that he considered Mulan his friend at that moment instead of doing at gratitude and compassion). I also really find it pity and unfair that Yao, the meanest and my least favorite of trio, got the most devoted love interest and won the heart of girl the quickliest.
On other hand, Mei has one redeeming quality, while Merida doesn't have them to me. Mei'sredeeming quality to me is this line, "I just wanted to compliment you.You were so brave to take your father's place in the army. Your duty was to stay home but your heart told you to break the rules." I love that Mei compliments Mulan not for saving China but for taking her father's place. I love that Mei sees Mulan's joining army as good act and not as bad one which was redeemed by saving China. I think her perspective is not so common in universe. Mei deserves a credit for this. I really wish somebody had said something like that to Mulan in the first movie.