To be honest, a little too over the top to be particularly convincing. The whole family were like caricatures. The one thing that makes this worth watching is Majandra Delfino. She is the one believable character and she really has a quality that keeps you watching. Between her singing and acting, it staggers me that she is not more successful.
The 70's setting also works. The movie has its moments in between the weak bits and hammy acting, but I couldn't seriously recommend it.