Not much has gone wrong with this car. The only thing wrong is that the undercarriage guard has loosened up and slaps the oil pan loudly at certain engine speeds, creating an ever-so-annoying vibrating sound.
Since the car is, after all, AWD, the tires are prone to wearing rather fast under hard driving. Only about a year after buying the car, I had gone through two full sets of tires, but to be fair, I was kind of putting the car to the test, driving it hard into long, twisty corners repeatedly. Since those incidents, I have not had to change the tires outside of my regular maintenance schedule.
Exterior wind noise is absolutely disgusting. Exterior noise was very inaudible in the beginning, but as time progressed, noise around the front of the front doors just became louder and louder. At high speeds, the noise is just unbearable.
This car is not what you would call "refined" or "perfect", but I mean it when I say it's SOLID. The interior design is slightly bland, but everything works as it should. Front legroom is great, and rear legroom doesn't suffer all that much unless the front seats are pushed far back. However, if you lower the driver's seat down enough, the rear-left legroom decreases dramatically, and comfort is virtually nonexistent.
Trunk cargo room is EXCELLENT. I can fit anything from tons of groceries to large boxes in the trunk with ease. Rearward visibility does decrease a little bit with taller loads, but the side-view mirrors take care of that well. There's also a cargo cover that retracts over the trunk to keep items from sun exposure or wandering eyes.
The air-conditioning/heating system works well. The control slider for changing the temperature is the traditional mechanical type and does feel pretty cheap, but works nonetheless. The air conditioner works consistently and picks up fast, likewise with the heater.
This car packs a huge punch for such a small engine (only 4 cylinders). Acceleration is excellent, and as you'd expect with Subaru's AWD system, traction on almost any terrain in any weather condition is excellent. Road grip and handling is strong, and there's not much over- or understeer. Braking is OK; it's not great, but is still remarkably strong for an AWD station wagon. Torque steer is virtually nonexistent as well.
This car is also extremely safe and reacts well to sudden driver inputs. I have been rear-ended three times, all of them substantially hard impacts. The first two literally didn't do anything to the rear; no scratches, nothing. However, the third was an impact of extreme proportions, and left dozens and dozens of deep scratches and chips in the bumper. The muffler was knocked completely out of place and was replaced, but its mounts are bent and it now sits slightly tilted. The car comes with front driver and passenger airbags, and safety ratings are excellent.
Like I said, this car isn't exactly refined or perfect, but it's SOLID.