Ask HN: Is Webix worth buying?

I was blown away by their demo but I take it with a grain of salt, and want to see if it's really as good as they it's portrayed to be by asking the community. Has anyone used it in their projects? I'd rather use Webix than write something from scratch using AngularJS although, if there are alternatives to Webix that touches on the same things it does I'd be open to that.