Well, I guess this is going to be a common thread theme...already some in the forum regarding this question.
Mine, a 2011 X3 2.0D, had already two rear brake pads sets replaced (at around 19000kms and then at 41000kms aprox.) and on set in the front (around 27000kms)
This is really something that is just annoying...in 18 months that I've been driving it, already spent almost 700euros in brake pads replacement alone...I guess this is the way BMW compensates for the 5year/100000kms regular maintenance only pack included when you buy the car...