I just installed this OS on my Curve 9370. It hung up on the setup screen had to reboot and was a little slow at first right after upgrade reboot, but improved to normal after 2nd soft reboot. It was communicating with the network too, so this may have contributed to the hang up and/or slowness.
This update has some new features, I dont what earlier releases have as I havent used them and went right to this one. I am aware that most of these will come standard with 7.1 OS now or some point in another upgrade. The features I have found right away without digging deep are...Emergency Alert Message feature on "Home Screen", BB Device Anaylzer, Battery Saving Mode, Mobile Hotspot, Payment and Billing