This is a common part which tends to wear heavily ( especially on the heavier sport tourer )..
In my experience
Apart from the creaking the car still handles well in the dry.
Mine passed it's MOT with a worn bush but not sure if this is because the suspension design at the rear of the Lag is relatively new or the tester did not look properly ( or both ) ??
BUT ( IMHO ) does not safely handle when cornering to the left in the wet or your rear os / ns wheels hit pot holes , bumps etc..
Can lead to back end skipping out suddenly..Could lead to an accident for the unsuspecting..