I'm running BBM5 on a Curve 8350i w/4.6 and I actually have installed it twice now. The first time I loaded it, loved it, was playing around with it and tried to "send location" to my gf... yeah, not so much. Locked up my phone to the point of just constant reboot. Hd to wipe, reload, basically start with my phone like it was coming right out of the box brand new. Royal PITA in other words.
But, for the 6hrs I had it the first time, I just loved the new version so much I actually reloaded it. It runs fine, hasn't slowed phone, no issues whatsoever... just dont send your location!! Or maybe I just have a bad copyof it. apparewntly its a known bug (at least according to one of the other forums), so I just dont press location!