As google plus has many advanced features which can be used for business effectively. You can do online business meetings , through videos you can make your business popular. And many advantages like these.
It depends that which kind of changes FB show , and how much these changes be useful for visitors. If people like that changes , then FB get advantage. As an example , before sometime when g+ launched ,FB has tried to change its home page look and try to show its all facility on home page. But this change not liked by people , instead of that it be more confusing for people to visit any direct location.
G+ is yet to start their platform for businesses.. But surely it'll be quite effective once its out !
Google plus can be effective in online business to generate traffic for a website buy followers of circle needs to be of a website niche type to earn expected benefits.