Works great, have tons of new features and new UI. Grab it while you can at http://0mietechsupport.wordpress.com/2009/07/17/bbm-5-0-for-all-current-os/
I had a hard time running it on 5.0.0.100 OS on my Bold, but it turned out the one for Tour (4.7.1) OS works fine on 5.0 OS with Bold. Time to enjoy BBM