I was hovering between "neutral" and "not in favour", but eventually I voted for the latter. I don't begrudge the actual show (watched it once, didn't see what was so special), or even its fans, truthfully -- I can't think of one fandom that doesn't have a side helping of batshit crazy somewhere. What really, really annoys me is the exposure MLP gets. It gets shoved in my face whether I'm interested in it or not. I don't mean avatars or anything like that, but seriously, I visited some meme site not so long ago, and somebody had uploaded pony variants to every entry I looked at. Every. Entry. Then there's the people who use pony-related slang in completely unrelated, irrelevant topics, like "anypony" instead of "anybody".
Basically, what frustrates me is how usually, things like this tend to stay in their own corner of the internet, where all the related forums and fanfiction and whatnot are. If you don't like it, then you don't go there. Instead, it's like MLP has grown past that corner and is encroaching on every other area of the internet as well, and you're going to constantly be reminded of it and see it everywhere regardless of whether you like it or not. I don't hate the show or its fans, just how it's everywhere.