I honestly feel it's too late for BBM to enter the market. It would have still been fine if they released the app when they had originally planned. I think they delayed it by over a month and I have no faith in them.
They really needed to make the original launch date to overcome the idea that they're constantly late in shipping. Many have a "believe it when I see it" approach to BlackBerry at this stage, and who would blame them? This is apparently a rolling release, which shows that they're being cautious. You also wonder if this release will drag out for a while, if something goes wrong this time, too.
1 month too late? Try 5 years too late. $BBRY should just give up and try to sell off any remaining IP they have left. Don't see BBM generating any real revenue for a company that is already experience extreme decay.