Same problem here. If I turn it on, it shuts itself off after a while. I only use it in my car so I don't notice it right away but everytime I enter my car, I need to turn my bluetooth back on. REALLY annoying. There's a post on reddit with a lot of people experiencing this issue.
I have a Pebble watch that has a special vibration when it isn't connected to Bluetooth so I tend to notice during the day when it Bluetooth dies. It happened three times yesterday--one apparently at night. Normally it doesn't matter, but when I'm driving and it isn't connected, it can be a bit of a bother.
My problems started after the upgrade too but it's slightly different. I am no longer paired to my car but I do not see a keypad to enter the code on my phone when I try to pair it. I suspect it's an overlay issue but cannot figure out how to see the keyboard.