The Piaggio is spacious, relatively speaking, for the rear four seats. Typical cabin configuration has two side-facing seats forward, one by the door, and a bench seat that fits two facing the door. These are cramped. The lav has plenty of room, but segregates someone sitting there.
The airplane is relatively quiet, but not nearly so much as is advertised. The quietness of the cabin has more to do with reduction of wind noise than the aft facing engines.
Wind noise from the door seal is a perpetual problem, especially in the winter.
Checking the oil requires climbing up on the wing, removing 15 special internally-threaded expensive screws, removing a panel, then unscrewing a cannon plug from the dipstick, and finally checking the locking dipstick.
External baggage is nice. Weak latch and locking mechanism.
Expensive carbon fibre brakes, no antiskid, and they get touchy when they get warm. Won't hold when they're cold. Hard to get replacements or overhaul.
Parts availability can be an issue.
Flies nice. Not bad single engine performance for a light turboprop twin. 500-1,000 fpm.