Hi. I've been testing Bluetooth with this new release cm12 based and I can confirm (at least in my n5) two things:

-One good: connection now works way better. I mean, now I can connect and disconnect to my car audio and it stays working. Music sounds great!

-One bad: audio when making a call still has issues. An ugly noise over the voice as in cm11 based.

I'll keep testing. Great work guys!!!