When the concept of Google+ was first announced, I thought it wasn't going to threaten Twitter at all.
With its emphasis on Circles (the segregation of groups) and privacy, I thought it would more resemble mass texts or email blasts. Twitter, on the other hand, is more of a PR tool (for businesses) and shout-out-to-the-world platform (for individuals).
However, Google seems to have plans for Google+ to fulfill the PR/shout-out functions of Twitter plus more.
Google recently announced it will eventually allow business users to have Google+ profiles. Ford and Mashable, meanwhile, already have theirs.
Google+'s Huddle chat capability has potential for webinars, analyst calls, even customer service [uses] for people to have a face-to-face experience of the brand, Ford's social media chief told ClickZ.
So there's already one advantage Google+ has over Twitter for corporate users.
In addition, Google+, in all likelihood, will eventually be integrated with Google Docs, Google Calendar, Gmail, and who knows what else.
The point is that while Twitter offers you 140 characters, Google+ could offer you the world.
Then there are the advantages of segregation. For example, Ford can have a general public Google+ Circle and Google+ Circles for each model of its vehicles. That way, customers can receive tailored messages from Ford, which is something Twitter can't conveniently do.
Google also has the potential to integrate Google+ messages into Google search in a way that's more attractive than the search and hashtag function of Twitter.
So Google+ will definitely have more bells and whistles than Twitter. The only question, however, is whether or not it'll be better to use.
Google's own search engine homepage has shown that a simple but robust service can win the day. Twitter, therefore, could conceivably have the perfect combination of features as the world's PR/shout-out tool and would beat out Google+ for that function no matter what fancy features Google+ rolls out.