Despite its imperfections, which in my cursory understanding are largely academic, Telegram is an amazing messenger. It's very quick, feature-rich, and developer-friendly. Perhaps best of all, it's a nonprofit. So I can expect, with a high degree of confidence, that the organization won't abruptly switch course one day to appease investors.
1) no video calls
2) voice calls just now being rolled out
3) encryption is opt-in and limited to one-on-one conversations
4) requires a phone number for authentication
The "academic" criticism is about its crypto being poor. The rest is regular stuff which is a deal breaker even for many non-academics.