I'm bullish on Pinterest not only because my wife and I use Pinterest for everything from planning our wedding to finding outfits and meals, but because I market on Pinterest for a few clients all day long. It consistently brings in more traffic than other sources when you do it right, even for clients that are ranked in the top 5 in high-traffic Google SERPs.
The crazy thing about Pinterest traffic is that it never dies off. If you get a bunch of repins today, traffic will be showing up from those pins months later; it's kind of absurd, and very unlike Adsense or other discovery advertising platforms in that way.
The difficult aspect for Pinterest will be getting the worth of Pinterest ads down to a final cost per action since it is such a long wait before you see how much each pin is truly worth. And that really is the goal for any advertiser: If I know this click will bring me $2 I'll pay up to $1.99 for it. A lot of Pinterest users are in hardcore discovery mode, and as such Pinterest traffic doesn't convert as well as search traffic immediately, but in the long run it always seems to be worth it.