S. Tuner is for those who have knowledge of sound. This is not just for tuning but for understanding the quality of your instrument. By watching wave form and frequency map, you see - purity of the sound - overtones sequence and their duration - change of tone
These are basic factors to determine the quality of your instrument.
For easier tuning, special skins are designed for some instruments like "guitar", "base guitar" and "piano".
In settings, you can set various options for your interests.