BBM's advantage is security, but not sure if Android/iOS's BBM goes through the BIS servers that BB version does. And then there's the PIN number, it's really not that different than using a hotmail address or something for Skype (Who in their right mind uses a hotmail addy for their main email), and with Hangout the only concern is the phone number however I only SMS/Skype with people I already know, BBM is probably better for talking to people you met on IRC or at college or something. When I was a BB goer I had over 60 BBM contacts mostly coworkers, family and friends and some were people I met at seminars, conference, golf tournament, coffee shops, etc. I remember that RIM had to shutdown BIS over in the middle-east because insurgents were using it to communicate while the US military couldn't intercept their messages.