I found WhatsApp useful to keep in touch with my relatives. We created a group and it was very nice to have everyone being able to read everyone's messages at once.
When I found out Facebook bought WhatsApp, I deleted my account, pissing off a few of the relatives who took it personally!
I went through hoops to delete my Facebook account a couple of years ago. I didn't want that to happen to my WhatsApp account as well.