I've had Editor for years now, and it is, without a doubt, an essential tool that I use on every project.
As far as people saying "it's quicker to record that part again"... well that depends. If you know your way around ME and know how to use it's tools effectively, it's faster to fix in in ME than to set up to record a part again. If, however, the glitch is a big one and the note needs to be moved more than a whole step or perhaps more.... recording again is the best option.
I have used it to:
stretch a note played by a sax. it was a quarter, needed it as a whole.... worked fine, sounded good.
change chords as mentioned from original to something else.... mostly moving notes half steps.
moved audio in time... notes that we slightly off the beat, slide them to the beat.... flawless.
deleted notes from piano and guitar chords to make the chord sparse.
fix bad notes in bass or other instrument tracks. (sometimes I just do copy/paste)
Increase the volume or decrease as needed of a note or phrase.
smooth out vibrato in a singers voice.... lessen or increase it as needed. mostly lessen
fix other vocal glitches... not sure what they are called, but not vibrato or pitch issues.... totally fixable with care.
fix vocal tracks that are slightly off pitch... totally transparent. (this is my main use of ME)
create a harmony vocal track from the original melody vocal track (note: this one had artifacts as the original notes had to be moved a fair distance. By keeping the harmony volume low, the artifacts are not as blatantly obvious. see "Come & Go" on my music site.)
hope this helps. It is indispensable to my work in the studio.
BTW: every bit of that is done manually. I do not use the automatic correction mode at all ..... I stopped doing it with automatic a good 2 years ago. Much better control over the process when you go measure by measure, and track by track that needs ME's help. It takes a bit longer but the time and effort are well worth it.