If I started getting lots of invites from people I trusted, then I might consider joining. But I'd never even heard of them before reading this article.
LinkedIn goofed up ONCE in allowing your face in ads when you have some connection to the company. That's nowhere near as slimy as Facebook putting your face on ads you'd never even CLICKED on (famously a woman saw her HUSBAND in a picture advertising a singles site...), and that's just the tip of Facebook's privacy betrayals.
And since LinkedIn has a totally dominant market share (and mind share) in "business connections," it's going to likely take a lot more than a better design and easy import to dethrone them.
It looks like the hook is "use us to host your online resume! We'll make it pretty!" That approach has some potential; I'll keep my eyes open for a Zerply-hosted resume moving forward.