Google+ Comments will let you show comments made on your Blogger blog post, Comments on the blog post that you've shared to Google+, and Shared content on Google+ that links to your blog post, all in one place beneath your blog post.
Google+ Comments look similar to traditional Blogger comments, but of course similar doesn't mean exactly the same. With Google+ Comments, now when you leave a comment on a blog post, you'll be opted out if to also share that comment to Google+ or not. Google+ posts that link to blog posts will show up as a comment underneath those blog posts, and if original comment is shared to Google+, replies to the comment on the blog will show up in Google+ and vice versa, but only to the people that the original comment was shared with.
But i guess this is the bad point: If a comment is not shared with you (Exactly the blog author), you won't be able to see the comment neither in Google+ or even on your own blog post. It's not good, this can't be real..
As the blog author, you'll receive Google+ notifications when a reader posts a comment or share your blog post. Changing your blog's url will cause existing Google+ Comments to disappear. If you are considering moving to/from a custom domain, or changing your blog's url, you have to do that before you enable Google+ Comments.
Circles will still be applied to a Google+ post or comment when it appears on Blogger. It means that if Somebody posts a comment on your blog or Google+ post and he only shares the comment with his Family circle, the comment that will show up on neither your blog or Google+ post will also only be visible to those who belong to his Family circle, you won't be able to see that comment but those who belong to his Family circle, unless you too belong to his Family circle. Once again my friend, this can't be real..
How To Activate Google+ (Plus) Comments?
It's easy.. Just visit your Blogger dashboard >> Go to Google+ tab, and check the box to enable Google+ comments. But note that you have to connect your blog to your Google+ first.
Moderate Google+ Comments On Your Blog
~If you are the original author, you'll be the one to receive notifications about any comments and be the only one who can moderate comments. You can enable email notifications through your Google+ settings.
~There is a little difference to moderate comments here, if previously you moderated comments through the Comments tab on your Blogger dashboard, now that you'd like to enable Google+ Comments on your blog you'd moderate comments directly within the blog post itself. The Comments tab that previously you used to moderate comments will now be removed from your Blogger dashboard, but you can still get it back by disabling Google+ Comments.
~You can moderate comments by clicking on the drop down arrow next to the comment, or by hovering over the comment and clicking the "X" that appears.
~Comments that are considered as spams will be hidden, but you can review those by clicking on the blue Review Comments bar, and edit them in bulk.
~You can remove comments from your blog only if the comments are shared publicly (Or shared with you), you'll not though be able to remove any comments that are also shared in Google+. Can't be real..
~Readers will need a Google+ page or profile to post a comment.
I myself have tried this comment system, and it was not working properly. The comments already made on my blog as well as the new one that i made to test it didn't appear, and i didn't find out why. Some bloggers out there also experienced some issues with Google+ Comments. But, maybe you can try it yourself, you can still switch back to your default comment system right?
Tell me what you experienced with Google+ Comments. Feel free to post a comment and speak up your mind here.