BBM is my main form of communication with my family. I love that my kids can have it installed on their tablets and they can chat with me when they are visiting grandma's or when they're at home and I'm still at work.
That said - I'm not too impressed with the WP version yet. Part of that is just getting used to it - but some of the functionality and smoothness I'm used to from BB10 just isn't there yet. Like making a list in a group - it's a pain on my 830 and checking off the items is even worse. It's a list - why wouldn't you have check boxes?
At least I got my channels back !