I'm wondering if it's true usefullness is potentially in an Enterprise supplemental tool to cobble together some quick apps, maybe like what MS Access was used for a long time ago, except this time you get nice browser-based, reactive applications.

I'm not sure you'd use it to build the infrastructure of your startup on. Or a content heavy site. But I see building tools like for managing a lot of developer instances, internal tools for config, etc to possibly be pretty sweet for this.