I don't use it with iMessage, but I bridged WhatsApp, Telegram, Instagram and Facebook. It works quite well, but I uninstalled it after maybe 2 weeks. There are too many features (understandably) missing, like surveys in WhatsApp, these bot chat buttons in Telegram and calls in general. And having the original apps and beeper installed defeats the purpose for me personally.
I had to wait maybe 3 weeks after signing up.
What's with all the 3rd party clients for ABS on iOS? Pretty cool, and unfortunately that there isn't much going on on android.