As with any publishing platform, the value of Instant Articles greatly depends on your business model and goals. https://blog.bufferapp.com/facebook-instant-articles
Deepest engagement for the longest period of time happens in Apps, so Apps matter. http://venturebeat.com/2015/09/25/wait-what-mobile-browser- traffic-is-2x-bigger-than-app-traffic-and-growing-faster/