Haven't been doing SEO for 1 year now but last time I did the +1's would give a significant boost.
For example a keyword that has 10k searches a month in a SEO competitive niches.
I was able to create an article of 800-900 words keyword density of maybe 0.4%-0.6% (The keyword was also in the title)
Did all the tags and images optimization, hyperlinks follow/nofollow you know...
Sent a total of 5 links (1 website 1 link) from my PBN. DA50 PA66 (I think those were the numbers). 1 link, 2 days I pause before next link.
After 2 weeks 5th page.
After that I just barely got to the 4th page.(Maybe 4th-5th week) Enough time for the authority juice to flow through.
I had a small niche G+ page. Started posting my webpage link there. Was getting around 10-15 G+'s a day.
in 2 weeks was on the 12th place. Started pushing the G+'s started gathering more and more. 25-50G+'s a day.
Maybe I got a total of 350-400G+'s I had my niche website page on the 2nd place fighting against an authority website. (bodybuildingDOTcom or something I don't remember exactly.)
So yeah. If you use it for SEO they still have good impact. If you use for traffic I'm sorry for ya!