We have a 2008 Lci 520d M Sport and its a awesome family GT* car. My wife loves it and i doubt I will ever be able to prise the keys away from her. We had one problem with the turbo actuator going (but I am sure that could of happened on the 320d). Recently the rear de-mister relay went. On my previous 530d, I did 65k miles and only had a DSC sensor fail.
The biggest win over the 3er is space - the boot is longer/wider eg we can get a mclaren buggy in length ways, in the 3er its at an angle. You can always stack it to the roof with the cargo net keeping the cabin safe. It also handles well and flows nicely on the A roads. Its not as agile as a 3er, but its not far behind and the ride is far smoother/less crashy.
*I say Family GT in the sense that its (just) fast enough and cruises very comfortably at 70-80 and with the family aboard why would you want to go any faster than that.
Few practical pics:
