[inthewoods]

Here's a chart of Facebook's overall app score according to Applause Analytics over time (since 2011). It is an abstraction on the generic star rating.

http://i.imgur.com/iB2SMwC.png

What it shows is that there has been a general trend down in their app score - there seems to be a further dip around the time of Messenger but the reviews seem to indicate a lot of frustration around stability.

[morpher]

For apps that have been popular for a long time, I wonder if there is a negative bias in reviews (beyond that already present in all online reviews). A customer who gets an update that breaks an app they use every day is very likely to submit a negative review (even if they have reviewed positively in the past). However, a customer that gets and update that make incremental changes that largely don't affect them has no incentive to go post a positive review of the new version. So, the positive reviews come only from new customers, which are relatively small for apps that have reached saturation.

[inthewoods]

One interesting sub-trend in the data would support that view - it is that the review star rating, meaning reviews+star rating is, on average, more negative than just star rating. So people post a negative review when they feel pain, but not in the case where they are just rating the app.