PigPen is a theatre collective that started as a rock band (and the band still plays occasional gigs when the group can book one on a night they're not performing as a theatre collective. Their shows seem fairly low-tech and end up being somewhat more than they seem. They do stories that work for children but which also have adult appeal.
Patrick's review summarizes what you'll get quite well, from my own experience of the show when it played The Old Globe last summer. If you think it would be dreadful, you're better off staying away. But, I can tell you that the actual experience will be diverting and clever enough that you'd probably have a somewhat more positive opinion coming out than you did going in.