I come from a Honda family, owning an unkillable (and I tried) Accord before the BMW, and so my standards for how a car should be built were set a little high. Most people "warned" me about buying a used european car claiming I'll be on the side of the road or with a monstrous repair bill in no time, but my BMW is still running strong. However, if you want this car and have low maintenance costs, be prepared to do a little work yourself. Labor is where shops will overcharge BMW owners and so doing basic jobs like brake pads or changing the oil will save you a ton of money if you do it yourself. Take care of it and it'll last longer than most cars on the road.
The mileage (25 city/31 hwy/28 ave), the handling, the grip with 17" M rims, the compact yet usable size, the comfort and luxury features. Plus the smooth, strong power mated to great 5-speed transmission and great brakes w/ABS & traction control completes the whole package. Great sense of safety.
Cupholders aren't useful, but few imports in the 90s had ones that were. Rear seat is small, but sedan has the exact same interior measurements as coupe (except with a little more rear headroom). Better headlights as US plastic ones always look murky.