Although not X1-specific, I've been watching a fairly in-depth exploration of the iDrive system which covers the X1, X3 and X5 (and others). It's handy for me as my 2006 530d doesn't have this generation of iDrive, so it's my first exposure to it really (apart from the X1 test drive). I'm really looking forward to getting my hands on the real thing in a couple of weeks time!