I'll have to listen to this again when I get home, because I've never heard what you're talking about. She's no Mariah (or Beyoncé) when it comes to demonstrating unostentatious ease, but she does possess about as much ease and flexibility as you're going to see in a full lyric soprano, and there are multiple examples of her performing very difficult intervals with aplomb. In fact, the only time I've seen her struggle with a song's demands is when she sang what appeared to be an impromptu cover of Mariah's Emotions on one of those Asian variety shows.
I don't recall if she used crescendi on her belts in that performance, but I do know that if she did it was a conscious choice and not a crutch. She is nearly on Beyoncé's level when it comes to her control of dynamics, and she doesn't need to crescendo (or scoop) to reach her top notes or achieve power.
And tone is purely subjective, but on a personal note I think she has a gorgeous, crystalline tone, especially in her upper register or when singing lightly, and a beautifully supported scale throughout her range (sans a bit of the lower register).
But perhaps singing a mediocre Celine Dion song was not the best introduction to a goddess like SoHyang. Have you seen this video? Her control is machine-like (TM Leona).
