Notify for Spotify displays a notification when a new song is played in Spotify. Compared to other notifier apps, it allows you to skip songs directly from the notification and also provides an optional menu bar app to easily control playback.
Notify for Spotify is also more robust when switching to new songs from within Spotify's search feature compared to other apps — Spotify doesn't make new song data immediately available, so other apps either display no notification or display "Unknown song".
Compared to other miniplayer / menubar apps, Notify for Spotify's main focus is on unobtrusively notifying you of track changes so you don't need to dedicate screen space to a miniplayer or click into the menubar.
Note: Notify for Spotify is a third-party app that is unaffiliated with the company Spotify AB.