Joy is approaching your house on foot from about 1000 feet away, not being able to see your X3, but knowing it's there, just over the brow of the hill, pressing a button on your iPhone and then waiting, waiting, waiting, then BEHOLD! The xenons light up the night sky! Not once, twice but thrice!
What I'm trying to say is that yes, the BMW Remote iPhone app works.
Haven't tried the remote horn sounding yet because I didn't want to annoy the neighbours, worry the wife and wake up the baby