There are 117 miles of it altogether! Mostly it is open and even when it looks stationary you still move faster than on the parallel roads. I live just off J20 and saw it from the very beginning. Watford was joined up early on and before the M1 was connected.
Traffic through Watford was a nightmare before the M1 was eventually joined and I spent most of my last 10 years of working life commuting from home to Feltham via the M25.
Because of the relatively slow journey to work, my automatic 2 litre (company car) regularly ran at over 40 mpg. It was this journey that made me choose an automatic for my next car, as I had counted up the number of gear changes (300) I did on the each trip and guessed that caused my left knee to ache. The excellent mpg carried on for the automatic as well.
One of the problems are the local drivers who pop on and off for just 2 junctions, this slows the traffic at each junction and the lorries have to slow and speed up again which takes time, and then the M25 gets back to normal speed.
There is a low background hum which you do not notice until you go on holiday! On balance it was a good idea but the media love to criticise or try to tare things down which promotes the odd problems into being typical of the norm.
Regards
Roy
