Native English speakers, how do you feel about the use of "gonna", "gotcha", "gotta"...?

Maybe it’s just me, but I feel that it is a bit too casual. It looks like some kind of slang. In short, I don’t like it.

One of my classmates uses that a lot, almost everywhere. I know she is heavily influence by pop songs and pop culture. I have heard her say “gonna” many times during a presentation. She never uses “going to”. And that annoys me a little since we are at a presentation.

What do you think of the use of “gonna”, “gotcha”, “gotta”...?