It's something for girls who like fairies and magical things. Well, more for girls who like cool villains actually, and the movie delivers its sparkling dark style perfectly. If it entertained me it will entertain your younger ones.
If we're speaking of quality story development and such, it definitely needs some major reworking. Plot? No sirs, it's gothic glam from here on out. I especially liked how the dark pixies' base was some hypnotic night club and their only weapon seemed to be dance. That was a nice touch.
Don't think too hard and you'll enjoy it.