JK Rowling promotes mostly positive values of love, friendship, courage, resolve and perseverance, acceptance of those who are different with condemnation of bigotry, and that we all have a bad side but that we should overcome it as we are defined by our actions. So overall I'd say her message is a very good one.
The only quibble I can think of offhand is the implication that people should marry almost right after school. I also couldn't help but notice (and mocked in a story of mine) how often the bad guys (male and female) were blond though she did ease up on that about the same time she introduced Luna.
Note, I'm not saying JK Rowling actually preached this stuff (much) just that these are the values (or "author's DNA"as Mister Love calls it) imparted into the stories. I got worried when my 12-year-old was promoting Twilight but felt good that she admired Hermione Granger and remains academic to this day believing you can be smart, valuable, and likeable.
mile: (Btw, the negative messages for females is a big reason why most fundies leave Twilight alone while the positive messages for females is why most fundies attack the Harry Potter series. Because Harry Potter isn't dangerous to kids, rather fundamentalist Christians, including fundie Catholics, are.)