I'm pretty much open. I wear a variety of pony shirts when I go out. MLP isn't that popular where I live so the chances of people recognizing my shirts is very slim, but when people do ask about it, I'd say it's a good show.
My cousins, all younger than me, would ask why on Equestria do I like a show "for kids". I told them to try and watch it and see for themselves, they still don't get it, but they don't make fun of me.
My parents are okay with ponies. They're quite proud of the fan-stuff I've put out and I'm happy. :3