Cant comment about auto v manual, as I've not driven the auto.
What I can tell you is the bullit proof reliability of the car if properly looked after. My own one is a 91 3.0 with approaching 150,000 miles. No real issues so far, and still enough performance for me Don't let high mileage put you off, just ensure its received the appropriate TLC over its life.
Good luck
Current toys= MV Agusta Brutale, BMW K1200s, Mini cooper SD, Jaguar XF, Ex S2000 owner
91 NSX Owner between 16 July 05 and 18 Feb 2011