This isn't really something I can go in-depth about, so I'll try something different.
This may be a bit more of an editorial about the fandom than a review, so be aware of that.
Season 4 is just around the corner. And what better way to celebrate than sitting down to one of the year's best animations? It's got cute art, a relaxing tone, and smooth animation. It's not gonna tide you over until season 4, but in this fandom, there'll always be something. That's one of the joys of being a brony: There is always something new to watch, or read, or listen to, or even play. There's a whole world of pony out there.
But not all of it is good. While many of the things in the fandom are well-made, entertaining, and creative, there's also a large wealth of things that are also a lot of things that are incompetent, boring, generic, or otherwise not enjoyable. That's part of why we're here-to point out the good and warn about the bad. But maybe you hold different opinions from one of us. That's fine. "Just Relax and Pony" won me over with its charm, relaxing tone, and great animation, but maybe that's not enough for you. Maybe you want videos with more happening. In that case, "Just Relax and Pony" isn't for you, although I'd still suggest checking it out, because it's only 1 and a half minutes long and won't take up too much of your time.
There's a world of bronies and brony stuff out there. It doesn't matter if you start here, or if you started earlier, or if you never stopped. There's friends to make, videos to watch, music to listen to, fanfiction to read, games to play, and friends to make. So remember to sit back, relax, and pony.