Not very precise.

Has a tendency to switch between strum and individual strings too easily. It is easily confused by background noise in live situation (for tuning an acoustic guitar with a microphone).

But worst of all, it is not very accurate even in one string at a time mode. I can easily hear the string being sharp or flat while this software will show it as perfectly tuned. It sort of "locks-in" when nearing dead center even though Im not touching the adjust key anymore...

The strum feature is nice as a novelty but not accurate enough to get your guitar or bass perfectly in tune, so not worth $10.
I will continue to use Peterson Strobesoft which is far more precise for the same price.

Thealien666 about PolyTune