It works stable and fast and it also already perfectly scales down to a mobile format. In Desktop mode it looks a little bit too "empty" but scaled down it perfectly fills the space. So some motion and Project NEON stuff should work for this so that the App is more satisfying while using. Also don´t forget to have an eye on the Windows Feedback Hub. There will be Feedback.
Ps: Enabling it for mobile (ARM) will also bring benefits for the Windows 10 on ARM devices this fall.