Been using this lately and what a great tuner. The polytune function is great, as are the on board features of chromatic tuning, drop tunings, light sensitive display, choice of stream or needle view, true through by pass but to name a few.
I am using it for standard and drop tunings ( semitone flat), set to polyphonic, and on needle view. You can view it as a needle or as a stream when it is in the chromatic mode of single string tuning which it does automatic for you.
For me its asset is the polyphonic function. Quick strum of all the strings and the display shows all strings and their tuning.
If one is out as soon as you target that string the tuner goes to chromatic mode and shows you that string and that string alone. After tuning a quick strum shows all the strings again, great tuner, fast and accurate.
Changing tuning parameters is easy a basic one switch to open up the options and plus minus to your choosing option. Its standard default pitch is 440Hz but will calibrate between 435-445 Hz.
It handles extended ranges with ease, and even the fretless had an intonation problem on the D string which was picked up and correct with a slight adjustment of the saddle.
It can re-set the polytune mode to read E, D#, D. C#, C, or B then when you look to tune a single string it reads as a standard chromatic tuner.
The great thing i like is when in chromatic use in any drop tuning its give you the correct note pitch not the altered one. So when i play a drop tuning like semitone down and set the tuner to this, the polytuner recognises this, but when i go chromatic it read my bass as D#, G#,C#, and F# it true reference to standard not an altered reading of E,A,D,G.
That might seem a trivial thing but it does get confusing sometimes when guitarists give out dropped tunings according to the fretboard position not the pitch.
If i have a five string on then i do not re tune or drop tune i have the extended range to handle it from standard.
The amount of times guitarists have given me the wrong "keys" at jams because they are dropped tuned well.......tuning a guitar a semitone down means you are a semitone down on fret position.
When they say A and we start to play, they then seem to want to mention the fact they are a semitone down..........mmmmm then that's not A is it?
So as it tunes guitars and basses this might remind a few guitarists that all they do is change the position of a note on the neck of the guitar when they retune, a minor thing but one that will develop good habits.
All in all it handles extended range easy, i even re-tuned my standard to B-E-A-D with no problems it reads string intonation great.
Battery access is easy from the bottom using a coin to unscrew the single big screw that holds the plate in place. The battery is easy to install and the compartment easy to access. Screw back up and continue.
Metal case construction is solid as is the button, a single pole type, easy to press off and on very solid feeling.
The display is light sensitive so its brightness is adjusted to suit the conditions and help save battery life.
Changing the parameters is easy done with the two small buttons, left and right of the power inputs on the front side...does exactly what it says...changes values up or down, very simple to use.
With true bypass, it is hard wired across the input and output so your signal when not using the tuner does not cross any of the circuits or boards, so it is a purer sound and better connection as the circuits do not take any part of the signal.
Now i must admit i would never really notice this with my set up, but if used in a multi pedal board it is a useful feature. Also as a little extra you get a velcro strips to attach to it and your board, so that saves a bit of messing about.
DC power in and out so it can be in-line to daisy chain other pedals. Battery low warning appears on the main display in clear large letters as BATT so easy enough not to miss.
Instructions very straight forward and enough examples to guide you on a single page op info rather than War and Peace to wade though.
In all its a great option to consider (£75 approx) and will give any tuner a run for its money and more because of the polytune function which is no gimmick. After using one i feel it will become a standard thing on all tuners to be polyphonic...it just makes sense.
takes abit to get used to but its quick for tuning 
