«  Breakfast convenient, accurate »

I use it for a few days on my electric guitars.
The pros:
small
solid
precise
s'accorche at the head of the instrument detects the note by vibration (or something like that then used in a noisy environment)
clear display
well-lit
Cheap

The -:
the screen does not rotate 360 °, thus compelled to find the right position so that the widget fits well on the head and the screen is visible in playing position,
a bit long to relax sometimes
I also had a little trouble finding the right place to fix it on the top of my TV.

I would do without this choice problem (or so I'd take the version with swivel head)