No it currently isn't permanent but it will be at some point in the future +Claytonian JP
Ensure that you send in feedback on what you like or don't like about the new interface, and what you think is missing.
To activate the Feedback Tool type an @ symbol outside of a text entry area, or click on the link at the bottom of the left side menu. https://support.google.com/plus/answer/1678224Be sure to send in one feedback for each feature you're talking about so that it gets sorted correctly. If you send in feedback about multiple things it may only get recognised for the one thing.
Here is where you can find out more about feedback and see your past feedbackhttp://www.google.com/tools/feedback/intl/en/learnmore.html
Feedback is being actively monitored for users thoughts on the new Google+.
Here are some of the changes that are happeninghttps://support.google.com/plus/answer/6320397?hl=en&ref_topic=6320376
To return to the Classic Interface follow the link at the bottom left of your web browser screen when you open the left side menu. This option will not last forever, so sending in feedback on the new interface is important.