From my opinion, I gladly say that the Winx Club is a very well-built, loveable series. My favorite season was the first one, so I shall be reviewing based on that. It all starts like a typical normal person-to-hero story, a normal girl named Bloom who discovers her powers one day, after a boring normal life. The storyline continues, where Bloom and the rest of the Winx find their true selves through friendship and teamwork. A great attribute about their team is their diversity. Layla/Aisha comes from an African descent, Musa from Asian, and Tecna from British. They each learn to respect one another and use their differences to make up parts of their group. They fight different villians and go through events that help further shape these values.
About the supposed issues of inappropriateness for children, I must say that some of them are overexaggerated. The stereotypical teenager girl (as some would put it) is actually the image of a teenager that is seldom seen in society today. Girls today think much more about inappropriate topics for their age, and going out to clubs and other dangerous places. These girls are in fact innocent if you compare, spending their free time giggling and joking around, hanging out and shopping, ot having slumber parties and grabbing some pizza. Those were the fun times, and they are living it as well, I consider this a good example of "having fun".
Their appearances can be an issue depending on how you look at it. They wear "skimpy" outfits, with physiques of models. If you are worried about your child going anorexic, you should also worry about them trying to fly or throw fireballs. These are cartoons, not the actual person. Their relationship with their boyfriends are also considered an issue, but instead this shows a healthy relationship. They care about each other and model what a true bond is like.
Overall, I think that the Winx Club is a nice cartoon series with fascinating elements. The animation suits fine with me, and I have quite grown attached to their fairy forms. I would recommend this to anyone, especially the Rai English Version. 10/10 :)