Philip
Welcome to Pprune! I hope you find it enjoyable and informative. There are a great number of highly experienced people here and others like yourself just starting on the first rung.
You will see from the responses below (that come from both ends of the spectrum) that this is a subject that has been very well discussed and you will find a wealth of knowledge and debate if you use the search function above.
To save this attracting any further biased comment I am closing it!
HWB