Mine's done about 1700 miles, and yes I do think it's loosening up, particularly in Sport mode. I'm loving the smoothness of it; it doesn't snap your head back like my 335d, nor provide the soundtrack of my 135i; but it is a magnificent engine in its own right
Still very happy with mine, usually at this stage I'm wishing I'd got something faster; but for what I want from my car now, it's pretty much perfect! I'd class it as the best all-round car I've owned