I looked at a 355 and 360 two years ago before buying my first F-Car. After driving both cars I opted for the 355. Not withstanding the design preference the 355 felt more "visceral" and the way I expected a Ferrari to sound and behave. I have about 24K on the clock now, including a cross country trip, and the car has been wonderful with very little service issues. IMHO the 355 is the last modern day era Ferrari worth keeping - the new cars will basically have a maser motor, etc etc. Take your time finding the right car. Do the PPI, look for books and records, and everything else stated here. Don't let the headers be a deal breaker - if you do break one, just get some from QV and your done with the issue for life. Great car. You will not be disappointed!
Spent my first weekend with the 355. Really enjoyed the car! Much more driver friendly than the 348 by a long margin. Still need to get it registered so I'm a little afraid to drive too much. Car is beautiful, so much so that my sons brought several friends to see it. All needed a ride. They didn't do this with the 348 for some reason. I cleaned the engine which was followed by a rather substantial oil leak. Can't seem to track it down yet but I will. Overall, the car is far superior to my 328 and the 348. I am not disappointed in the least!