heavy WhatsApp user here as well, and I have the total opposite experience, WhatsApp has greatly improved since then. End-to-end encryption, group chats and voice are all working really well right now.
1. I know the people working on this and they really care.
2. It would be a pretty big fiasco if they lied on e2e encryption. You can assume that people are actively and periodically reverse engineering their mobile apps, so this would surface at some point or another.
