Been using their bridges for over 2 years, super happy that I no longer need WhatsApp installed on my phone.
If you're like me and live in a country where a shitty chat application is required to be able to function in society, software like this is a breath of fresh air. The bridges are also super stable and incredibly well written.
Note: to be clear, I don't use beeper itself, but use their open source bridges (what beeper is using internally) on my own self hosted Matrix server.