IMO, in the current pitch-correction landscape, Melodyne is incredibly overrated. I havenât used the polyphonic stuff, so I canât speak to that, but the UI, and more importantly the UX are absolutely awful. sure, you can âget goodâ at using them once you figure out a workflow that works for you, but thatâs not the same thing as being designed well to begin with. itâs ridiculously unintuitive, and the menus in the editor window are put together in about the dumbest way I could imagine.
the UI is hideousâobviously thatâs a very minor gripe, but itâs just not appealing to look at, and kinda sucks the life out of any session where I know Iâm going to be spending a lot of time working on edits. such sessions are inevitably preceded by an audible sigh, and a âwell, here we goâŚâ
but the most important thing is that the sound quality isnât great. itâs Melodyneâs strongest suit, but thatâs not saying all that much. lots of artifacts, and audio behaving in weird ways/not as youâd expect, which then requires more fidgeting to get it closer to doing what you want (if you can at all). canât tell you how many times Iâve had to throw up my hands and say âgood enough, I guessâ to get a basic correctionânot even an aggressive oneâto sound natural.
itâs actually the main reason I moved away from Ableton LiveâMelodyne is the âbest in classâ VST pitch editor, but itâs an incredible pain in the ass to use. the best pitch editing Iâve used has always been proprietary within a DAW. I still havenât found anything with a better workflow, that beats the sound of Reatune (which is also ugly, but I can forgive that, since itâs got such a friendly workflow). Cubase has a little bit of a learning curve to it, but not bad overall, and once you understand it, itâs every bit as good as Reatune in terms of sound quality. still has some quirks, but overall, quite good, and better yet, integrated with Cubase. 
would love for them to add polyphonic editing at some pointâhopefully Iâd continue to be lucky enough to not have to use that very often, but it would be a great addition.