I know, these days, Facebook has a pretty bad reputation because of all the issues related to data leaks / manipulation around the US elections. Undoubtedly Facebook has to do something to protect its users' data integrity. But Menlo Park's powerhouse remains a tremendous tool for advertising and... analytics purposes.
Here are 5 reasons why you should plug Facebook Analytics to your app (mobile SDK) or website (PIXEL).
1° their SEGMENTING tool just ROCKS.
Facebook Analytics enables you to segment your users based on events and other default traits. You can save your custom segments and apply them to all the views you'll get in the tool, for instance the user retention view.
2° You can leverage DEMOGRAPHIC data from Facebook's user base
Whether you like it or not, almost all of the developed world is on Facebook. So you'll get a pretty good picture of your users based on the data collected by Facebook (age, country, city,...).
Tip: also use FACEBOOK AUDIENCE INSIGHTS in Business Manager to learn about the persona of your competitors' users (and of your own users once you get a sufficient sample).
3° You can create CUSTOM AUDIENCES straight from Facebook Analytics
You'll be able to use these audiences for retargeting purposes in Facebook Ads Manager. You can also create lookalike audiences based on your custom audiences, to drive your acquisition campaigns. Please note that you need a sufficient amount of users in a specific segment to create custom audiences (at least 5K users based on my experience).
4° Facebook Analytics has an EVENT COUNT operator
It's not even something coming out of the box on Mixpanel (you need to activate the counter for specific events)! You get by default an EVENT COUNT operator for each event recorded on Facebook Analytics. It's great to create segments of heavy users and analyse their behavior (e.g. "show me users who have made at least 5 trips in my travel app").
5° You can create BREAKDOWNS for each event, in a snap
It's a great feature to see the age breakdown for a specific activity or the install source. Unfortunately Facebook isn't a universal attribution platform. It will only show you details for Facebook campaigns :-( (You'll need to use an attribution platform like Kochava, Appsflyer, Adjust, Tune,... for a full view of your attributions). But if you're a Facebook Ads heavy user, you'll love the off-the-shelf granularity you'll get from Facebook Analytics breakdowns.
One last thing...
You can also use for free (as long as it lasts) the push notification and in-app messaging features integrated with Facebook Analytics, a great alternative to premium services. The only tricky thing with Facebook is that you're never sure that their tool will be available forever (Parse, their Backend-as-a-service, was for instance discontinued, much to the dismay of a lot of app developers). So I advise use to always have a backup plan.