To at least add a contrasting point of view, I've never had a serious issue with my '98 M3. I've had the two routine services done that they recommend (Inspections I & II for stuff like fluids and belts retuning the engine), plus the oil changed a few times and maybe break pads once.

Only non-maintenance issue was when I spilled coke into an airbag-related sensor in the seatbelt. Not exactly their fault.

So I've had a great BMW experience. YMMV (and obviously has).

John