Hmmm, my take is that her transformation is like Princess Diana. I mean Lady Diana Spencer, whom transformed little-by-little from royal girlfriend, fiancee, to wife! Ahhhh, those were the days.
I recall my first impression upon seeing Lady Diana being mobbed outside her apartment because the press found out she was seeing Prince Charles ~ I turned to my big sis and said "she's not a teenager, she looks like a grown woman!" Honestly, I couldn't believe she was a teenager like me and my five brothers & sisters.
That initial impression over, I thought her very very shy, and rather plain. Then next I saw her and Prince Charles's official engagement pics and interview, and thought "she looks even more of a grown up, like a matronly woman, with makeup on this time". Then that impression was quickly followed-up by her first official function with Prince Charles, wherein they met Princess Grace. That's when I felt sorry for her, she looked awkward and a tad chubby in that low cut black strapless gown, which did nothing for her imho.
Finally, I'll never forget me and my big sis staying up all night & day to watch her wedding to Prince Charles, we honestly couldn't believe it was the same girl!!!!! OMG, seriously, she had transformed overnight, like magic, into an honest-to-God fairy princess. It didn't look like the same woman at all, this was a young girl, gorgeous, fairy-like, otherworldly, truly the stuff of dreams...
Anyhow, that's how I see Charlene's transformation. Of course she looks nothing like when she first met the prince. She's grown up and matured over the last 5 years, and so has her style, including her hair, clothes, posture, makeup, et al. But she still retains that innocence, charm, shyness, humility, which I love. And I can only imagine what she will look like on her wedding day!