UPDATE: The issues I had have been addressed! Thank you! Five stars!
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First, this is the only BPM app (by tap) I've found that calculates BPM to two decimal places. I need accuracy, so that's great. But beyond that, there are puzzling caveats:
1. The app has a bizarre connection with the loathed Game Center. Why does a BPM calculator need Game Center? There's no explanation for this in the App Store, nor in the app itself.
2. After calculating the tempo, you have about two seconds during which time you have to write down the tempo somewhere (or quickly memorize it), because the app automatically resets and STOPS displaying the tempo it found!! This is aggravating.
Developer, please fix these annoyances—and I'll gladly give 5 stars.