I love using it in my creative writing, I use it for an abrupt change. Find it kinda weird that it's so controversial.
My 10th grade english teacher (2002, just as blogging was taking off) called it sloppy and I gotta agree with her. These days I see it as youtube punctuation, like jump cut editing for text.
How is it sloppy?
It's not. People just like to pretend they have moral superiority for their opinions on arbitrary writing rules, when in reality the only thing that matters is if you're clearly communicating something valuable.
I'm a professional writer and use em-dashes without a second thought. Like any other component of language, just don't _over_ use them.