Worth a try. In addition to strengthening the back and stretching, it includes the development of dexterity, coordination, a sense of rhythm, and artistry. Even after exercising for 1-2 years, you can get good physical training and strengthen the muscle corset (which is necessary for everyone). But you need to pay attention to the choice of a coach. In some schools, children are "broken", giving a huge load immediately and incorrectly, they can also crush psychologically. It is important to choose an experienced professional.
Worth. One of the few sports that gives girls much that they need. Stretching, plastic surgery, a sense of rhythm, strengthening muscles without their growth, tightening. Moreover, this sport is quite symmetrical in the development of the body, unlike, for example, tennis. Rhythmic gymnastics is not as tough and traumatic as sports. Plus by 20% it is also dancing with choreography, which may well be useful in the future. Well, there is work for the result in any sport. If you don't like it, quit. Do something else if it is done for health and harmonious development.
My daughter was engaged. Then she quit and went to the dance. In the first six months, she overtook those in the group who had already been seriously engaged in them for several years. She stepped into several categories at once. The preparation really affected and helped. She has achieved some results, and now she regrets again that she quit gymnastics. But it’s too late to come back because of age.
If, of course, you want a champion, then you should prepare for sacrifices and pressure. And start as early as possible. Years from 3-4x. But my opinion is that a child should be engaged in sports for general development, and not for the result. It should be fun. The result is stimulating.