I made a post in the software section under "Auto tune" just last week and I left my observations on the Celemony forum at the same time.
All of this was just coincidental to this thread.
I also searched out opinions about Auto Tune vs Melodyne and learned that with the advent of the latest bloated version of Auto Tune that a lot of guys that have both are dismayed at the performance of both.
Shouldn't be too hard to learn about.
A brief synopsis would be:
1) Timing drift issues abound.
2) Sacrificing satisfactory single note melody correction capabilities for the promise of polyphonic fun and games.
I gave Melodyne Editor 2 years of optimism and then last week I used Acronis to restore and old closet classic DAW to a state where I have a licensed version of Melodyne Plugin running.
Got to go... guests arriving.
all the best,
mike