Who's using BBM on Android ?

I'll freely admit I'm still trying to wrap my head around BBM. I was never a BlackBerry Messenger user in the past, and it's entirely possible I won't be in the future. But obviously someone is using BBM — the app passed into the 5 million to 10 million downloads category in Google Play in just its second day. There's no denying how impressive that is.
Those who know and love BBM continue to sing its praises. Those of us who don't are still wondering what the big deal is.