I've been running the ROM Manager version for a little over 12 hours, so it's still way too soon for me to give any good reviews. I will notice that first impressions seem to greatly increase battery life and some transitions (opening apps; switching between apps) seem to be noticably improved. I'm coming from the d1 where I ran BB for nearly it's entire lifespan. I'd stray occasionally, but would always come back to the stability of BB. Looking forward to the developmental progression of the Nexus and 4.0 with BB.