Do you tell your brother that you don’t like his fiancé?

Do you tell your brother that you don’t like his fiancé?

"My brother is about to get married and I think he’s making a huge mistake. His fiancé has this way about her where she feels like she’s better than us and she makes everything about her.
I’ve only met her a few times, but I’m concerned that my brother doesn’t see what we do."