The diodes from generator burned at 60,000km. It cost me 2 days from my vacation, 40 euros for a voltage regulator that actually was OK, and 100 euros for a second hand complete generator removed from an old Omega.
The radiator fan switch started not to work properly at 70,000km. Cost about 35 euros to replace with original.
One pressure limiter for right back wheel brake started to leak 70,000km. It cost about 10 euros to fix at a local shop. (Opel dealer was not able to fix it, but did worse).
Shocks absorbers needed to be replaced at 80,000km. (the original ones were still OK, but the roads are very bad, and the 195/60 Goodyear tires were not very comfortable either).
Plastics from the car started to crack or not to serve their purpose. (put some glue, or removed some)
The muffler had some weak points. (I had to welded it twice)
Driver side door handle (from outside) has a broken spring and the handle feels loose.
Transmission always had small shock when putting from D to R. Also, when running down hill without pressing the gas or the brake (but in Drive), the shift from 1-2 comes with a shock (feels like a kick back). Also the program selector has some faults when manually selecting 1 or 2. Had it "fixed" with Opel service. Still has random problems. I change oil quite often in the transmission. Recently I upgraded from Dexron 2 - Dexron 3. Feels better, still is getting brownish too soon.
The resistor that selects the speed of the fan in the cabin burned at 80.000km. Cost 25 euros to buy a new one. I replaced it myself.
Air conditioning is not efficient, probably because of not enough Freon.
Small oil leaks from head gasket. Some rubber tubes for recirculation of the air cracked.