I've only so far been using this software to play around with at home, but I do intend to use it live and in recordings in the future.
I purchased this as it's the same autotune/harmoniser software used on Bon Iver's song "715 Creeks". It's a little intimidating when you first open it, but like anything once you give it a little time its quite easy to use. There's also a lot on online resources on how to use it if you're really stuck with it.
It's a really fun software overall. You can add harmonies to anything, not just vocals. You use it as it's own instrument and run an audio track into it, so it's really creative and fun to play with.
Cons:
My only annoyance with this, and it is a huge one, is you need an iLok to authorise it. It is such a pain to have to pay another ¤50 for a silly little USB stick and then have to register that and then authorise your software. Buy an iLok with this software, otherwise you can't install it.
Overall, if you're into effects and weird sounds, get it, but remember to get the iLok.