Vanity metrics look good and tell you nothing. The number of downloads tells you nothing if you don't know retention. The number of users tells you nothing if you don't know which ones are active.

The metrics that matter are proxies for the outcome you actually care about. Work backward: what behavior indicates that a user has gotten value? Measure that.

For most products: DAU/MAU ratio (stickiness), NPS (do users recommend it), and churn rate are better leading indicators than sign-ups or downloads.

See: [[pmf-signal]], [[@james/revealed-preference]]