This latest build for the fast track is the most stable so far. Battery life is better, though not perfect. That also has to do with the types of apps run (Facebook, Tweetium seem the most labor intensive). I have had far fewer restarts and freezes that aren't related to specific apps. That said, occasionally, media still bind each other up a bit. Bluetooth does not always update quickly when devices are turned on. For example, a long-running issue is Bluetooth headphones/amps. Sometimes Bluetooth sets up with just voice connected. Shortly after, music etc. are added and set to go. This kind of wait should be eliminated, though it is more an annoyance than huge problem. However, I do have one complaint with the install. It reversed the Quick actions I had lined up in the Action Center! Not a huge deal, but I had WiFi/Bluetooth/Brightness/Flashlight/All Settings. After the update, it was completely reversed! Meant a couple times my trained right hand thumb accidentally turned off WiFi until I realized they were reversed! As I said above, this is a very stable build, likely nearly RTM for the Anniversary Build in Redstone. Had the 950 shipped with this build, there would be far less crying and moaning about that phone.