I also have a polytune clip, which has seen a lot of use in classrooms. The polytune feature is basically useless on a ukulele, and the price is quite high, so this 'unitune' one should be very good.
It's sturdy, has bright lights, the display automatically flips right-side up (so you could hang it on the backside), it's economical on its battery, has very few and countersunken knobs. It is able to handle a different calibration (changing from A=440Hz for playing along with 'odd' instruments) and one thing the manual doesn't mention is that it can work on vibrations (clip) as well as on sound (an internal microphone).
The Peterson strobe tuning system is a bit of an overkill on ukuleles, unless you really want to finetune a saddle. Also, some letters are a bit harder to decypher (B and Bb, and D, basically because they're represented as lower case letters), and the # symbol is a rather small dot; but once you know that it's a perfect little machine.
As said, I let students use mine in class from their first lesson, and contrary to other tuners this one holds up well and helps them a lot.
