Following it's release just a couple of weeks ago, Google Plus is already being tipped to compete with the seemingly untouchable Facebook.
Google Plus is currently invite-only and is being used by a minute selection of the world's population (mainly internet professionals). However, don't get too excited if you're lucky enough to receive an invite, as Google will only let you in when it opens registration for short slots every few days.
The network itself is very impressive! The interface is clean and simplistic, there is an option to categorise contacts within 'circles', there are lots of great features (including excellent chat and video chat capabilities) and it can be integrated with other great Google services.
I've only spent around an hour going through Google Plus, but based on my experience, I would say that Google Plus is designed to offer an all-in-one culmination of Facebook, LinkedIn and Twitter. If you know someone who has access, I would strongly recommend pushing for an invite, as there is nothing worse than being the last person to use something like this and it is pretty good.
A lot of people remain skeptical on Google Plus, after a number of previous Google releases, such as Google Wave and Google Buzz, proved hugely anticlimactic.
In conclusion, I think that Google Plus is here to stay and it will probably be used in addition to Facebook initially as there is still room for another mainstream social network. However, I think that if Google continue to invest time and money into their latest social platform, Plus could be a potential Facebook-killer.