Good non-anecdotal analysis by Om Malik1 on how exceptional WhatsApp is that it is worth $19 billion to Mark Zuckerberg.
Among other interesting data in the article, two interesting facts:
- WhatsApp has nearly 500M users after 4 years of founding. (It took Facebook 6 years to reach that point.)
- Monthly active users per employee at time of acquisition was 8 million users per employee, the most efficient in the market. (For example, Facebook has less than 500 thousand users per employee, and Snapchat less than 1.5 million.)