The Google+ launch has been well received and, for the most part, I have been very impressed by the product (it feels more complete, usable and social than other recent Google products). But they still have a long, long way to go to earn share from the social giant, Facebook. I am not saying that Google+ will take down Facebook (far from it), but here are five reasons not overlook it just yet. I think that Google has created something that lives between Twitter's public world and Facebook's 'private' world - and they will arrive upon interesting use-cases / audiences:
Universal, new header that extends across Google properties and their enormous reach
From the header to the search results: promotion / inclusion throughout the SERPs
Ability to create a robust contact platform - between GMail, Google+, Apps, etc
Notifications are key to engagement & retention. Google has ample opportunity to deliver notifications: email, screen real estate, etc
Mobile: we know a hefty percentage of Facebook's activity is via mobile. Google has enormous reach as well (Android, iOS, search, etc).
Also worth noting the new mobile header / cross product promotion for mobile