If your car runs okay, the only thing to really worry about is accidently knocking your tranny into neutral while driving with the cruise control on. Without this switch working, you cruise will just run the engine RPMs to the limit.
If you recently did work on your tranny, I'd just check to make sure you plugged it in and also check to make sure it was tied off away from the exhaust. I failed to do the latter and my plug melted on the exhaust.
------------------
351W 89 Mustang GT Convertible