This unhappy girl is actually a good card. Why people don't run it is besides me, jk. Okie this card is okie not good.
The best case scenario would be to get her out with a dream sprite. Using the both of them will make sure that the Unhappy Girl's effect comes to life. Once you get the Unhappy Girl's effect off you'll need to have some support cards. Such cards would include:
The cards listed above are very good in making her deadly. So if you want to use her by all means do, just ask your self this: is it worth it?