The 12 simultaneous tuners is a bit of a gimic. Due to harmonics, the strobes for notes other than the one sounding seem to show a tuning match - or near match.
Never the less, with the widget on the right side accurately identifies the fundamental, so the tuning is fast and accurate.
The reference can be shifted from A440 to between 415 Hz to 455 Hz.
The auto-octave works very well. So far I have seen no reason to lock it down to one particular octave, but I like that the option is there anyway.
One of my favorite features is the ability to un-equal the tuning temperament. The menu lets me choose "custom" or "equal". When in "custom", each tone of the scale can be shifted +- 35 cents. And the "custom" setting are remembered even if I switch to "equal". It would sure be handy if there was more than one "custom" memory - and some common temperaments as presets would be nice too. Youngs, Kirnberger, Vallotti, Pythagorean, and meantone would be a decent short-list.
Because it will do any note, it works for any instrument. Banjo, ukulele, bagpipe, etc. However it's up to me to know how the instrument should be tuned.