I would like a real-time commenting system like what Google+ has. I actually think it leads to higher engagement. If Google decided to make it as a WP plugin, it would probably become more popular than Facebook's commenting system at least.
In my opinion it is a little messy only because when you load a page only the top few comments load, but as you scroll down to read more comments, comments that are replies to earlier comments start popping up, and it gets a bit overwhelming trying to follow a comment thread.
I like the idea, I jut think the execution need work.