My Little Pony is a quality cartoon for children of any age, or get this, gender. Its themes and lessons are equally valuable and the show is equally entertaining for girls & boys alike. I don't expect your son to start collecting the toys and brush the ponies manes of course or want his room to be painted pink, but as an animated show, this isn't going to hurt your sons masculinity any. The show has pop culture references galore for anyone astute enough to catch them, from I love Lucy to Big Labowski to Dr Who. The show isn't about dating or cooking, or slumber parties....(well there was that one episode). Shows range from fighting off sleeping dragons, how to handle one's pride, time management, finding out who you are by discovery, not being told, the downside of vanity, addresses prejudice against someone for just being different, how gifts can brighten other's days, how you should push yourself but not at the expense of your morals, just to name a few. There is plenty of action and adventure thrown in, and just a couple of cupcakes.
Unfortunately, thanks to society, and bullies, and perceived gender roles, if your male, or older child does watch My Little Pony, they should probably keep that information to themselves, I hate to say it and they shouldn't have to...but that’s how it is, and that fight against society should be fought by parents not fights on the playground. Just as a parent, if your male child shows an interest, don't panic or make him stop.
To address concern over Bronies, and fan made content, when you have an unexpected adult fan base, it's only natural to have the characters, sullied up a bit, and put into some adult situations. Everyone eventually grows up, and while some of the themes that adult community explorers are adult in nature, they are for the most part natural; fillies come from someplace you know. Does it mean that content is appropriate for children? No. That said there is a lot of really amazing, genuinely good, and safe fan content created as well. Take the bad with a grain of salt, if you want guaranteed safe family friendly online content for your child, that’s what the my little pony website run by Hasbro is for. No parent in this day and age should give their child unsupervised access to the internet, especially YouTube, let alone sites like Deviant Art.