It's beautiful inside. I don't know if they could have done anything better.
The door handles are oddly made of plastic rather than trimmed in padded leather or vinyl as on the previous 3 Series. The rear doors are missing the kick plates to protect the door sill. The door pockets are entirely plastic and have nothing to stop items put into the pockets rattling around (Though they've done this in the new 5 series now as well) These are all reasonable things they could and should have done better but it's about as long a list as I can think of. The rest of the interior is excellent, its well made, laid out well and iDrive 7 is in my opinion the best system they've done - offering everything you need and nothing you don't in a really logical and easy to use layout without looking like someone just threw a massive screen at the dash with no real consideration for how it then looked.