Busted drive shaft on front drivers side....how dangerous is it to drive?

i discovered today when getting my oil changed that the drivers side drive shaft on my car is busted. the car is still driveable and the guy at the sop told me it was 'reasonably safe' to drive so long as i went slowly over big bumps and avoided potholes. was he right? i am planning on just buying another car but need 2 know if it's safe to drive my car until then...