I thought it was interesting that this app still had no reviews so I downloaded it and tried it myself. This is a highly acurate tuner. It is a strobe type tuner that gives a visual tool to see what it is that the string is doing. This is superior to conventional tuners because strings don't vibrate at a single note they carry harmonics that can and do confuse electronic tuners. This is not for everyone though. It is complicated and offers too much information. This tuner is better suited for setting precise intonation by an experienced technician than every day tuning. At $20 I would have liked to have seen alternate temperments and the ability to tune around middle C in those temperments to better tune to a piano. but I guess it is geared toward guitar tuning and guitars are designed to be evenly tempered, other temperments would never work perfectly. still the ability to add harmonic stretch would be nice.