I've owned one since October of 2009, and currently I have about 55,000 on the odometer. These are the issues I've experienced over the years:
1. When the car was about one month old, a CEL popped up on the dashboard. This turned out to be a defective oxygen sensor plus something with the software. Covered fully under warranty, dealer replaced the sensor and reprogrammed the software, problem never resurfaced.
2. About five years later, driver's door lock began acting up (wouldn't lock or open when operated by the key fob). This turned out to be the notorious carbon build-up on the commutator of the servo motor that operates the mechanism. I fixed that one myself, never bought a replacement door latch. It took me the whole day to take the door and the latch apart, fix it and put it back together. A good, easy weekend project.
3. At about the same time, the gas struts that open the trunk lid weakened to the point that they were no longer able to lift the lid and had to be replaced. This is a 5-minute job once you have the struts, plus about $50 for the struts.
4. Six months later, glow plug on cylinder #1 went out. Local AutoZone store read the code for me for free, I looked it up in the service manual, ordered the plug ($100) and replaced it when the part arrived. Once you have the part, this is a 5-minute job.
5. At about the same time, I began noticing that when the ambient temp drops to about 50 degrees, the small LCD display on the dashboard will not illuminate. It will spring back to life when the inside of the vehicle warms up.
6. Every once in a while, the large display on the center console fails to show the time when I start the car. Turning the radio on and off takes care of this issue.
Other known issues with this particular model:
7. Oil leak around the turbo hose that connects to the intercooler's hot side. Virtually every car has this problem and the best way to deal with it is to disconnect the hose every time you change engine oil, wipe it clean and reconnect it. You will notice oil spot mixed with road grime on the inside of the plastic cover that sits under the engine. It is best to ignore this issue between oil changes.
8. Build-up of oil/water "snot" in the rubber hose on the cool side of the intercooler. The fix is the same as above - ignore between oil changes, but when you change oil, remove the hose, wipe it clean and reassemble. In cold climates, this may cause significantly more serious problem, as the water may freeze. If it does, the intake manifold will be completely cut off from air supply and the engine will not start.
9. Hiccups and stuttering when engine enters DPF cleaning mode. This is quite annoying and noticeable, but there is nothing you can do about this, short of DPF delete + tune.
That's about all I have. Overall, fairly trouble-free vehicle, but I still plan to turn it in next September as it is fiscally the best step one can take.