In shoujo, I find male characters like Kazehaya in 'Kimi ni Todoke' referred to as refreshing. I understand that to some extent it means that the guy is popular, but it gets on my nerves cause I don't get what exactly they are implying, especially since I've come dislike Kazehaya and some other 'refreshing' guys.

What people usually mean by this is that the character has traits and characteristics in their personality that are unique or not that common. In other words, they offer something new or at least something that isn't seen so often in their genre.

I guess in Kazehaya's case, it could be that you rarely see a popular male that is still humble and down to earth. Usually, in shojo, they are either the cool/mysterious type, or the arrogant and annoying guy that bullies his love interest. Kazehaya manages to be neither one of these cliches, thus bringing something new to the shojo genre table.