Hi there, right a quick buyers guide coming up, starting at the top....
-155's can suffer from rust in 2 main places, along the top of the front and rear screens and the inner and outer rear arches.
-inside, on the whole pretty hard wearing although the main panel for the climate control can be trouble some and electric window mech's can wear and fail.
-boot lid as lights on which are connected through a small loom which runs from the body of the car to the lid and with the constant opening/closing of the boot can break down
-under the bonnet, the 12v V6 is a pretty strong engine and cam belt failures are rare, however the hydraulic tensioners can leak and the water pump impelor can break away from the shaft causing seemingly in-explicable over heating, oh and they all rattle a bit from the tappets.
-gearbox is generally long lived as are clutches but it is a pretty nasty job to do a clutch swap if it needs one
-suspension, front, bottom arm bushes wear causing wandering under braking, vague steering and knocking, anti-roll bar links and strut top mounts are also prone to wear but the good news is parts are readily available and cheap
-suspension, rear, only thing really is trailing arm bearings will eventually fail causing excessive camber on the rear wheels, these can be a real bugger to change but again the parts are cheap.
-brakes, nothing much to report here, usual things to expect on any car, the occasional seized slider & hand brake cable although flexi's can brake down internally making it seem like the caliper is seizing as fluid is prevented from flowing back so the brake sticks on.
-electrics, on the whole pretty reliable.
-door mirrors can be trouble some, the alloy brackets seem to be made from some kind of cheese and as they age become very brittle and will break if you look at them in the wrong tone of voice.
think that about covers it, on the whole parts are cheap and readily available (at least here in europe) as there are a lot of shared parts with other Alfa's and Fiat's.
hope this helps but feel free to ask if there is anything else, makes it sound like a terrible car that is just waiting to cost you a load of money but they really are terrific things which will never fail to bring a smile to your face.
but in answer to the original question, yes, go fetch!