I just got my first BMW back in August, and without going into the long story, originally ordered it without xenons, since I figured 'Hey, I've had cars with regular headlights for years, how much can I possibly miss it?'
Then, when I had a chance to reconfigure the car, I asked here, and almost universally, everyone recommended the xenons. So I got them. They are fantastic. It makes a huge difference in visibility at night. They were worth every bit of the $900 lighting option. So add me to the list of people who will never go back to the 'regular headlights' again.