I've been a huge user of melodyne since the early days. I like that it's mostly transparent when used properly.

I used to use the shortcut of letting Melodyne Editor do the whole track using it's own discretion. That was fast and most of the time OK, but I was finding that I often had to fix what ME just attempted to fix. And the downside to that was, quite often there was no fixing that gave it a natural sound. So, at some point, I stopped using the auto-fix and started going note by note, phrase by phrase through the tracks that needed some help. Manually fixing a vocal track really doesn't take very long, especially if you ignore the stuff you see and simply listen to the notes and fix what needs fixing. And there's a few times that it's actually easier to do a punch in recording rather than to waste time trying to fix it after the fact.

The version I have is one of the early poly-chromatic versions. I have used it to edit piano and guitars and it does OK. It's better at removing notes from a chord than adding them or moving them more than a half or whole step. Handy for a chord that has a few unintended slightly sharp notes from aggressive fret-board string bending in the chord.

Always tune before you record or play. That's a lesson learned more than once. Don't rely on the old phrase the we can fix it in the mix. But if you do have to fix it in the mix, there's no better tool than Melodyne Editor.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.