I don't think Google+ should be trying to compete with Facebook and Twitter in the traditional sense of the word. Just because a website fits into a niche of companies under the broad heading, "Social Network" doesn't mean that it has the same intentions as its other incumbents. Facebook more or less eradicated MySpace because it was a case of two websites being too similar in function, and Facebook was simply superior. Twitter and Facebook coexist without one or the other being eliminated because they don't directly compete - Twitter is useful for different functions that Facebook doesn't accomplish; but neither does Facebook or Twitter
try to accomplish the other's specialties. While I agree that some competition is needed to expand user base and continually maintain attractive and trending features, it would be better for the social networks to specialize. A website like Facebook could never defeat Facebook - it has a de facto monopoly on vicarious, virtual socializing.
That said, you don't really go on Facebook to announce something to the world unless you have a really popular "Page" (as opposed to profile). You sign up for Twitter and tell your followers what the update is. It's much more professional for a working environment. Facebook is personal. I feel Google+ fits somewhere in between these two dichotomies right now, which is why it feels somewhat awkward for a lot of users. But I think it's still a very good network that has potential to specialize into something neither Facebook or Twitter quite accomplish yet. If it can create its own niche within a niche, competition won't be as important as maintaining its own superlative market share for specialized functioning. Otherwise, it will die out, because directly competing with Facebook will not work at this point in time.