I tried it with a song that is very familiar to me, "Antonio's Song" by Michael Franks, using the top hit in Videos for this Google search. It is in 4/4 time and the beat doesn't vary at all. It has five different actual chords: Am7, A7, Bm7b5, Dm7 and E7, and the pattern of chord changes is quite conventional in a verse-chorus structure. The algorithm did a so-so job of determining the chords. It rarely noticed that they were seventh chords, instead identifying them as Amin, Bdim, Dmin and E. It appears to rely strongly on the bass part. In one case there was a C# passing tone in the bass between an A7 and a Dm7 chord that was identified as a C#aug chord. I didn't try the editor. I guess this would make it easier than entering all the chords from scratch, but it struck me that there was still a lot of manual work to make it accurate and usable.