Elizabeth from Gintama -- good guy or bad guy?

I haven't seen Gintama, and I don't have time to watch it all right at this very moment (am going to start soon though!), though for a small project I need some info about Elizabeth. I understand the story arc -- coming to check out planet earth to try to take it over. But does the series make it clear whether or not Elizabeth has any interest in that? I know there is at least one other penguin/duck character that no longer wants to be part of the spy mission to earth.