Firebase has been able to help us understand reliably, the drop-off in our user flows with their funnel feature. This has made it easy for us to be able to pinpoint weaknesses in our funnel and test and optimize with data as the dependent variable.
From an economic standpoint, we don't pay for Firebase which is great, but as the saying goes "You get what you pay for" also holds true in this context. As we looked to grow and scale, we looked for a paid solution.
From a developer resource standpoint, Firebase has been extremely easy to integrate into our app. Whether it be the event tracking, dynamic links or crash reporting we have not had to waste too much developer time thanks to their well-organized developer docs.
Firebase was our sole data analytics platform through our Beta period which was crucial to make business decisions and adjust our application.
Because it was free it allowed us to focus on high priority issues instead of adding in a costly data analytics platform (which we finally did - Appsee and Appsflyer - which costs us now over $500 month so it saved us $500/month for about 4 months).
There's no way to directly correlate this to ROI but without Firebase's basic app analytics we would have never made core changes to our app or business and possibly still wouldn't be producing revenue today.
Google offers the Firebase suite of application development tools, available free or at cost for higher degree of usages, priced flexibly accorded to features needed. The suite includes A/B testing and Crashlytics, Cloud Messaging (FCM) and in-app messaging, cloud storage and NoSQL storage (Cloud Firestore and Firestore Realtime Database), and other features supporting developers with flexible mobile application development.