This is an interesting looking pedal and certainly very visually useful onstage under dim lighting - the big blue-dot matrix is easy to read.
I'm using it with a bass guitar and it's pretty responsive, both for generally getting in tune and also the regular use of drop-D, I'm still finding an optimum playing technique in order to pick up the correct note - harmonics seem a bit more reliable on a bass for example than open strings, and sometimes the tuner reads the note as sharp before it settles down to "in tune".
Elsewhere it mutes the bass safely and silently when in use, and you know where you are with the big footswitch. I'm happy to have it in my gig-bag.