Recent intrusive changes in the privacy policy of WhatsApp (including the sharing of never before seen amounts of unencrypted user data with the parent company Facebook) have prompted a mass exodus of WhatsApp users to the secure and open-source alternative Signal. I have been hoping for a change like this for years. I wrote a non-technical blog post about the problems with WhatsApp in detail, comparing the advantages and disadvantages of other messaging apps as well.
The sources:
https://arstechnica.com/information-technology/2018/04/hours-after-data-clash-report-whatsapp-founder-says-hes-leaving-facebook/
https://amsterdamtimes.info/after-data-clash-report-whatsapp-founder-says-hes-leaving-facebook/