We really do not know her personality, many people have drawn her image by a gossip press that has made criticizing her a million euro business. And that's not new, each candidate to Princess of Asturias suffered terrible attacks... always looking for the negative, the weak point to attack mercilessly. And that's the first reason why she is a good princess to Spain, she has endured all that pressure.
The Royal House has done a lousy job, they have put her in the background. They wanted to create for her a princess role of 40 years ago, not a princess role of 21st century.
That was not what most Spanish people wanted, and that's what the Royal House does not understand. Doing that only succeeded in creating a frivolous image, that only serves to make the gossip press make money. If they had allowed the princess to have a voice, be active, she has much ability to do things well and be well respected.
If anything recent events have shown, is that there were things that did not work well, and that the institution needed changes. And probably the Princess is more aware of that than other members of the Family.
Queen Sofia is hardly known outside her official role, makes little social life in Spain and has few friends. That keeps her from having many problems, but also alienates her from the reality of the country.
Urdangarín adapted to everything, good and bad, did not question the power, relationships or friendships, which gave him his position ... and that was his undoing.
The princess has adapted into many things, but also wanted to preserve a part of herself... probably is a more complicated way, but in the end is the most logical and allows a balanced lifestyle. Living enclosed palace is not an option, be adore by all with different intentions only for be a princess, either.