"Sometimes you just have to jump off a bridge and learn to fly on the way down."
The Japanese Mimi seems to me to be less of a complainer and less of a ditz - she's more of an ordinary cute girl, sometimes frightened and sometimes unhappy with her surroundings, but not always saying stupid things. She can be something of a tease and a flirt, and generally a typical little girl without being such an exaggerated stereotype.
Her crest was originally that of purity. Purity of heart/mind/spirit... I think to the Japanese, it's easier to understand, whereas an American audience would probably think that Purity is a weird chosen characteristic to have a crest for, especially for a child, who *should* be pure.
But Mimi's crest does not necessarily mean sexual purity, as Westerners might think. To be pure-hearted implies innocence, kind-heartedness, a good character, and sincerity.
Maeda Ai is Mimi's seiyuu (voice actress) and is a good one. ^_^. She is a great singer, and, along with performing the character songs that all digidestined have, she has sung many of the Japanese Digimon themes. Her name is sometimes abbreviated as AiM.
Mimi's character song is Itsu demo aeru kara. (She also has two shorter, alternate instrumental versions of this song, called Sweet Innocent.) For 02, it is Super Girl (somehow I think "super girl" fits Mimi's 02 image very well), and she also sings in a duet with Palmon, "Happy Smile". Apart from these, a few of the themes Maeda Ai sings include:
Ashita wa ashita no kaze ga fuku (Tomorrow my wind will blow - the first 02 ending theme)