The oxygen sensors went out twice on this car. Over heated, replaced the radiator and then the head gasket. Ran out of radiator fluid due to a hole in one of the hoses after the gasket was replaced.
We have always heard that Subarus were reliable, but we are now wondering if that's really true. The head gasket was really expensive to fix.
While I will not comment on the reliability of Subarus, your head gasket problem is not a fault of the car's design nor should it count against the manufacturer's quality measurement - that's what happens when a car serious overheats.