I have been using this site since this posted.
Here is what I have found out.
The traffic is bad for your site. It comes from one source, and unless you have taken specific steps with GA, will count as a bounce when they leave. For me at least, this traffic does not convert. Using this traffic increased my bounce rate and did not produce any sales. I did not leave it in place long enough to see if it would effect my Alexa rank.
The traffic and social media attention is primarily from members accounts, and a great many of them are marketers accounts designed for gaining points. The accounts come from all over the world too, so if international traffic looks bad for you, be aware.
I do not use the articles or link building features, but this is no reflection on the site. I do all that type thing by hand myself.
I do use the social share options. In particular, tweets, Facebook shares, tumbler mentions and stumbles.
Even though some of the accounts that share your link are from people like us and have no traffic value, they are legitimate social media shares, and there are many legitimate people sharing too.
From using the share features to get points back in the early days I can vouch for the accuracy of the count. I never saw a mismatch at all when I shared a site and earned my points. If it says it has been stumbled 200 times, it probably has, but many of those will be marketers accounts, so the total is irrelevant. What matters is that there are more mentions out there of your site for legitimate users to see, and that is not a bad thing at all.
I use it particularly to share out tier one web 2.0's, lists, and infographics. No traffic, no referrer, only get FB shares, tumbles, stumbles, and tweets (I don't do likes)
You can actually see the effect over time by using the site: command in Google, although it will not pick up nearly all instances in the social media world.
You can earn points in many ways, but if you decide to auto surf, use your anti-virus program daily (which you should be doing everyday anyway). Auto surfing this site for points without protection will get your computer infected. I auto surf with a crash dummy, and turnoff flash and java.
It will also stealthly download executables into your downloads directory (or it does with Crome anyway). After autosurfing, go into your downloads folder, sort by date created, and dump all the junk that suddenly showed up there.