It works most of the time, but sometimes it will perfectly display what I said as I say it, then respond "didn't catch that" and display "..." as my statement, having forgotten that it had already understood me perfectly one second before.
I have a 1520 and I have the same issue. Cortana loses connection to the internet if I am on wifi. If I turn off wifi, cortana works fine. I never lose internet access for other apps on wifi. I can browse the internet on IE, get weather, etc. Weird. I assume it is a bug.
My Bluetooth is on but not connected to anything.
I have the standard 940 from AT&T and I am using it, unlocked on AT&T in the DFW area.
I use on a PC and notice that frequently Cortana needs me to set her up all over again. I have to tell her who I am and what my location is. I've noted this even without restarting my PC. It's like she develops Alzheimer's.