You can start your own "collabs" and solos rather than just joining existing ones. Is it Safe to Use? This is the "fine print" you need to consider:
The 10.4.3 "Premium" version typically unlocks features that Smule usually hides behind a paywall: Smule Mod APK 10.4.3 (Premium).apk
The annoying pop-ups between songs are stripped out. You can start your own "collabs" and solos