the 100k standard at which a car is dead is now blown away by most accounts and cars are built to last longer then that. what they are not built for however is neglect
my own experiance w/ friends who have had subies is that the interiors start to fall apart, especially in the last 90's models. the carpets are about as thick as headliner material and most of the dash and console is cheap plastic, so it can start to squeak a lot
other things to consider, the diff, if it was not taken care of and had regular oil changes it could blow. if its a 2.5rs chances are its been beat on a bit, they arn't exactly the cars your parents would have bought.
other things - belts, hoses, plug wires, they can all dry-rot.
155k miles is a lot of miles to go accident or fender bender free, so look into that as well.
resale value. the average person under 25 puts on something like 20k miles / year. i have friends who do 60k / year. how long do you want to keep the car and at what price are you willing to sell it in 12-36 months?