The app is called Jasmine and MacStories has a great review of it. It's rather sleek and looks great. But what might be most enticing for people is the fact that it's free (although you can, via an in-app purchase, unlock parental controls and support the app which, if you like and use it, is something I recommend you do.)
At the end of the day, a YouTube app is a YouTube app. There aren't going to be that many differences between them. Just choose the one you like the most. Personally, I'm still just sticking with Google's app.