Here are some ways "quite frankly" can be used:
* To express a strong opinion: "Quite frankly, I think the whole idea is ridiculous."
* To be critical: "Quite frankly, the service was terrible."
* To be straightforward: "Quite frankly, I don't care what you think."
The phrase "quite frankly" can be used in both formal and informal settings, but it often carries a sense of confidence and authority. It can also be used to emphasize a particular point or opinion.