I am a beginner in vSZ. From my point of view, vSZ likes a wired and wireless management for business (medium and large). It will useful help you managing and provisioning those network. You can manage directly in vSZ web-interface, CLI, also via API where you can do programming.
SZ is hardware base, I don't have any experience about it. But, I see that it likes vSZ. However, it is builded by Ruckus both of hardware and software, so the quality is so good.