I've heard, but not really seen, that there are some fans going completely bonkers over this whole thing. If you do manage to see one of these people freaking out, just remind them:
* It won't affect the real show
* Let's not prejudge. That's what brony haters do isn't it?
* If you decide not to watch it, fine; but in avoiding it you remove any right you had to discuss it ever.
* If you watch it and hate it, great. So what? The simple solution is to not watch any more because... once again... it's existence doesn't mean anything for the real show.
I think of it as an animated fanfiction... Like friendship is witchcraft. Maybe it will be good. Who knows? But it's certainly nothing to get up in arms about. Save your pitchforks for Season 4 if Derpy is missing.