I have mixed feelings about it. It's cool to have something for young girls but at the same time it plays up the distinction i.e. "Leave us alone! Go play with your girly heroes!".
I agree. I like the idea of promoting DC's heroines, it's refreshing to see DC doing something upbeat and targeted at young audiences, and it's great to see the DC heroines wearing actual practical outfits instead of bathing suits and stripper wear. But I'm troubled by the idea of segregating "girl stuff" from "boy stuff." There's already too much of that in the toy and marketing industry. It used to be that toys, games, and the like were marketed to both sexes at once. Growing up, I played with LEGOs and Lincoln Logs and such alongside my sister and the girl next door (although they had Barbies and I didn't). These days, we have LEGO sets marketed "for girls" that are incompatible with the ones "for boys." There's an alarming amount of gender segregation and stereotyping in marketing for children, and from what I've seen, lots of kids don't like it and would rather be free to enjoy whatever they want rather than being told they're only allowed to like one set of toys or the other.
DC should present heroes of both sexes as role models for both sexes. Lots of girls like male heroes, and just as many boys would probably like female heroes if society would just stop brainwashing them into thinking they're not supposed to.