I'm surprised to see so many reviews praising the accuracy of this tuner. I've found it to be inconsistent about whether a note is sharp or flat, and in testing against my pedal tuner it is frequently wrong, even saying a note is flat when it's actually sharp.
Also, it's pretty bad at picking up low notes especially. I've found it very bad at picking up notes on a bass, frequently totally unable to pickup the low E string, so I usually fret it higher up the neck and tune to A or B. Though the rest of the bass strings are still inconsistent in getting a good reading as well.
And this is in comparison to other clip-on tuners. While all can be a little inconsistent, I've found others good enough to be my only tuner on stage. This kind of works as a backup, but I would not trust it as my only tuner.
I do like the tiny form factor, and the fact that it hides effectively behind the guitar headstock. That's why I was interested initially. But maybe the different construction is why it works worse than others.