Social business networking problems?

[Hunter]

So I'm doing a project. I've chosen LinkedIn, Craigslist,yelp and business social media sites in general. What are things related to people networking there work,company,or business related needs that you think this site does poorly in or needs improvement with?
Thank you so much, look forward to all the posts!!!

[robert m]

You need to do your own work but as guide:
what is their target audience? (eg linked in is professional business)
how do they reach their audience?
what services do they offer?

The compare and contrast.