I've got standard BT in my m135i as i refused to pay £450 for ext BT.
I use a kenu phone holder and stream my music spotify & iTunes by plugging a ycable in the armrest with a Tune2air BT device.
You hook up with both the car and tune2air together via BT and it works flawlessly. No messy looking aux cable running up to the dash and the sound is brilliant.
I also use my phone for google maps and if I'm listening to spotify google maps audio kicks in briefly over the music when giving audio directions. Take or make a call and as soon as its ended the music kicks back in.
Tune2air (amazon) £60 kenu phone holder £20 genuine BMW Ycable eBay £20.
Also list track info on the dash display, best £90 I've spent!!