Miserably bad.
This is the app you see in an ad and think to yourself, this is too good to be true, well it is. You can get better tuning results from GarageBand. Fake reviews, when I first opened the app, there was a list of “artists” recommending the app, one of them literally says “I am a real singer” and is called “John Adams”. I don’t even need to read the reviews to know that the 4.1 rating is forged just like their “artists” reviews. When did lying and forging become the standard?