It depends on the directory and how you're using it.

If you're using mass submission directories without even looking at it, then it's a complete waste of time.

At times, directory links can be good for local SEO (i.e. localized directories) but clearly, your site isn't interested in that.

I took a look at your site and you need to target large, powerful press websites. You've got a product that would do well from outreach to sites like Forbes, TechCrunk and Entreprenuer.com. Crafting a simple outreach campaign for editors and reporters would do you guys a lot of good.