I posted this yesterday night about my niece driving me up the wall.
Today we went to Disneyland and things went much better. She was good. We had to coax her onto the Haunted Mansion (What a meltdown), but she did great. Once we got her on every ride, she had an awesome time, and got more confident after each one. We've been sitting around the table and just talking to her about her life and it's so much better.
I think we've realized she is a little immature for her age, and may have some issues from her upbringing that kind cause anxiety and misbehavior, but she's a good kid. I still want one ;)