Guides hate them
Shooting partners usually hate them

It doesn't make your gun that much louder to you
If you're shooting a super magnum the brake can blow rocks at everyone in a small radius including your fancy optics (depending on design)

I like having them on rifles that kick more than .308 so I can watch my bullet fly and impact to get a good read on the wind and the fact that it's just cool to see a bullet dive into a target.

I could not shoot my magnums 40 times when I go out if I didn't have brakes on them. If you're a hunter that doesn't shoot a lot, I don't see the need for them.

There are effective brakes and cool looking ones and cool looking ones that are effective. :P