From an excerpt of David Rowan’s profile of WhatsApp, which was acquired today by Facebook:

We’re the most atypical Silicon Valley company you’ll come across,“ says Acton, a clean-cut, red-faced 42-year-old from Michigan, whose appearance contrasts markedly with Koum’s 188cm-tall, dark, unshaven look. “We were founded by thirtysomethings; we focused on business sustainability and revenue rather than getting big fast; we’ve been incognito almost all the time; we’re mobile first; and we’re global first.” He and Koum, he adds, are “the yin and yang – I’m the naïve optimist, he’s more paranoid. I pay attention to bills and taxes, he pays attention to our product. He’s CEO. I just make sure stuff gets done.

One of the reasons WhatsApp worked was its simplicity. There was no “bloat”, as the WhatsApp co-founders told Wired. That’s not a concept that’s usually associated with Facebook.