Adds noise into my signal chain when I'm powering it with the same battery that I use to power the rest of the pedals. Works fine with a 9V battery though, that's how I've been using. I recommend a filtered power supply for this pedal.
Doesn't track the low strings too well, switching to the multi string tuning when it fails to track a single string, which can become annoying sometimes.
Overall, it seems to be a tuner more directed for guitar players than bass players.