A gentlemen on one of my forums offered to teach people how to perform the valve adjustments on the beautiful little boxer engine. So I jumped on the opportunity. My bike did not need the adjustment yet, but there were plenty of other volunteers. A couple gentlemen even rode from Virginia and DC for the session and easily volunteered up their bikes.
We rolled up our sleeves, opened our eyes and ears and got our fingers dirty. We learned about removing the spark plug wires, plugs, valve covers, et. al. We learned a few tips and tricks on adjustments. We had educational discussions on too tight wiring harnesses, filing the air box cover so you don't have to remove the tank to reach the filter and packing for long distance trips.
Here are a couple pictures of the innards of a boxer:
So some may call them expensive or difficult to work on. But to me BMW just means Beautiful Mechanical Wonder.