My daughters' (ages 4 and 6) got some Groovy Girls for a gift a few years ago. They LOVE their dolls. We have a world of Barbie dolls (mall, car, house) & Hannah Montana dolls (and tour bus) and they all come second after the Groovy Girls. They are so great for body image too! They are "girls" not barbies with boobs. There are so many accesories, they have fashion, hobbies, they are girl scouts, and now they ride horses!!
We have the black horse and the brown horse and they are fabulous. The horse has a seat belt to hold your girl on, they make galloping noises and they neigh. Their mane is long enough to "style". No trouble keeping the girls on the horses at all - even while trotting along : )
I do not see them losing interest in the Groovy Girls toys any time soon!