A number of our users have these. Bob348, Bazil, Justynb frafreda, and nico.
Really there are not in major problems other than the regular maintance. Because it is a Ferrari it is high. But the 993 engine is a bitch to access and always has to be dropped to be worked on. This is a downside as you cannot do the work yourself.
Take a look at the "Tech Tips" section by clicking in the main naviagtion above. The last two tips are both for a 348. Hope this helps. Welcome to the site.