Another advantage, for those of us who spend part of our musical life playing with loud bands in loud bars, is that you can tune without being able to hear your instrument. [Yes, I know this is the Mudcat, but lots of us have a wide range of musical interests that go beyond the quiet folkie acoustic thing.] As others have said, usually some final tweaking is still needed, but in some of the situations I play in routinely, you wouldn't be able to get anywhere close without the electronic assist. I tune by ear in the relative quiet of my own home, but in the bars, the electronic tuner can make all the difference.