Why to create and use a Samsung account (on a brand-new S4 mini)? Are there any real benefits of (creating and) using a Samsung account? Or is Samsung just offering inferior services (e.g. "synch") in an effort to deepen its marketing clout?
As well as getting access to Samsung's sync and backup service, creating a Samsung account also gets you access to Samsung's app store. It's not as extensive as the main Play Store, but it has a good selection of apps.

Whether you think that's a "real benefit" or not is entirely up to you.