As part of the rare breed of people actually using Google+ proper, it's really turned me off from the whole thing. Even though I shared YouTube videos publicly and commented on publicly-viewable Google+ posts with YouTube videos, I intended to only post my comments and shares on Google+, not syndicated everywhere at a later date without additional consent[1] and especially not the cesspool that is the YouTube comment section. I don't really understand why anyone thought that'd be okay. And anecdote isn't data, but talking to other Google+ users I know, nobody seemed to be aware that this was going to happen: they all just thought the identities would be merged, but if you post on Google+, it'd stay on Google+.
[1]: I'm aware that there's probably some clause in their privacy policy that gave them the legal ability to do this, but Google is usually pretty decent when it comes to informing of changes to privacy/visibility options.