LOL... what feature isn't?

I think I have always said that it really rewards the better player, and has little impact on the more pedestrian. If you don't have much of a left hand, if you don't play a secondary instrument, if you aren't a bender heavyweight, if soloing freely isn't your strong point, no, it is of limited use. If you DO any or all of those things though, it is almost impossible to function at your best without it.

For jazzers, it has a great use... Play through the head, but keep the chord substitutions to a minimum. Then hit the CS, and then, while the rhythm section stays fairly straight, you can reharmonize, and get pretty outside, all the time the chord recognition is not going to go gonzo on you... Bi-tonality, whole tone stuff, basically everything you daren't play now knowing it will freak out the backing.

A million and one uses... or none at all..!