My wife's 2014 328xd only has about 45K on it. The one you purchased is one of the higher-mileage ones I've heard about. Keep us informed.
If older models with different engines are any guide, watch the harmonic balancer (crankshaft pulley), turbo oil feed lines, and NOx sensors. They re-designed the DEF/SCR system, so I expect it to be more reliable than the older ones.