Jo gives you most of the benefits of some of the big frameworks out there without all the fuss. Jo doesn't care if you dig rigid MVC, like object literals, wrap your apps with a module pattern, or prefer pure functional programming.
With a couple minor exceptions, Jo manipulates the DOM by setting CSS className properties. This means you can dramatically change not only the look of your app in CSS, but all of the animated bits as well. If you want a branded look for your app across platforms, tweak the CSS once and you're done.
If you want to customize your app's look and feel for each platform, most if not all of your customization will be in the CSS. If you're lucky enough to have CSS-savvy designer types on hand, this means you can more easily split up that work, too.