Suspension issues in cars seems to be coming more and more of a problem, especially in older vehicles. I believe this is partly due to the poor maintenance of many of the roads in the UK making it almost impossible to travel a few miles without hitting a pot hole.
Suspension problems can be a bit of a nightmare as often you cannot see exactly what is wrong with it without taking it to a garage. Many garages will look at the suspension for free for you and quote you on work that needs doing.
If you feel that the car is not handling as it should, is making knocking or banging sounds or is leaking fluid from this area then it is definitely worth getting it checked out. Coil springs are often replaced at the same time, but if you are only replacing one, then check as to if the new one is exactly the same as the one on the other side otherwise the car will not sit correctly on the spring.