I bought the tuner from Amazon because it's so easy to return if/when necessary. It was packed with no cushioning in an oversize box (not Peterson's fault). Fortunately, the Peterson OEM box is quite protective. I must say that it was not apparent to me that this was a reusable magnetic latch box. If I hadn't read that in reviews, I would have cut it open with my trusty pocket knife!
I didn't find the tuner to be easy to set up, either intuitively or per the manual, but then I'm not a hi-tech person (79 yrs old). I'm a former Tech Writer, and believe that most manuals are written by someone who knows too much about the product and subconsciously assumes too much. By reviewing the YouTube videos, I have it set up as desired to meet my needs.
I first used it on my electric guitars, and although it performed as designed, the difference between it and my Korg WT-12 and Boss TU-12 probably didn't make a big difference, considering the price of the Peterson. I'm sure it is as accurate as claimed, but that is a mixed blessing when trying to adjust intonation. The Peterson is finicky, as you'd expect it to be, and that extends the time required to tune/intonate an electric guitar. The guitars do sound great, but in a blind test, my ears perhaps couldn't confirm the improvement. The reason I question the validity of tuning a guitar that precisely is that as soon as my warm fingers hit the strings, they will go flat and my Peterson would be mortified! Also, I check intonation after each string change, always the same brand & gauge, and usually there is a little tweaking to do.
All that being said, the main reason I bought the Peterson was to tune my pedal steel guitar. I have the Korg WT-12 and Jeff Newman's temper tuning chart, and that gets the job done, but in a very slow and painful way. The Peterson makes me look forward to my next tuning! It is indescribably fast, easy, and accurate. Very satisfying! I know of no better way to do it. The tuner is well worth the money just for this purpose. I'm delighted with it! Buy one! I'll always have one.