I think for street driving, it's just fine. But I have seen them, been in them and instructed in them for Track and AutoX and - yuck! - particularly the earlier tips are pretty cranky for performance driving. The later 986/996/987/997 versions have a much better shift program. That being said, for street driving, cruising, having fun, it's a very good, very reliable transmission. I would just be wary if DE and AutoX are on your activities list.
The 993s are pretty bullet-proof cars - it was the penultimate air-cooled 911 design, and they have worked out many, many of the kinks. Some things to be mindful of on the air-cooled motors:
1) Valve guides. Particularly in higher mileage cars, this is the #1 reason for air-cooled 911 motor rebuilds
2) Seals and gaskets in low mileage cars - they tend to dry out when not driven regularly, and can give you problems
3) C4/C4s - I don't know if the 993 uses the same torque tube system as the 964, but they can be very, very expensive to replace/repair if they go bad
This being said, the 993s are pretty awesome and as a result, expensive compared to a 996, or even a used 997. But definitely worth it for the right car.
1998 986 Turbo-Look Cab
172,000 Miles
Dilithium Crystal Supercharger