alt Hacker NewsBusiness wise, neither Google nor Facebook were impacted IMHO. Google sells the tools that WhatsApp need to run and Facebook bought WhatsApp and kept its FB users in house.
Probably phone operators were not impacted too: SMSes bundled with flat plans are still flat plans and Europe style unlimited calls + 100 SMS per month plans are still there and those SMSes are still mostly unused.
So we could have a killer app and yet nothing changes in the flow of money around it.
UX wise, WhatsApp is a big improvement over SMS. Vocal messages, I'm not a fan of them. A waste of my time.
Google was impacted: their chat product is pretty much dead.
Mobile network operators lost the profits (at prices that were pretty much pure margin) they had on pay as you go messages, and messages not included in flat plans (e.g. overseas SMS's). They also lost a huge amount on highly profitable overseas calls. Those of us with family in other countries save a lot of money by using Whatsapp and similar instead of phone calls.