I did one the other weekend, largely out of curiosity. It was in the South Downs, 100 miles from Chichester. Obviously they are such a growth area, but I had fairly negative perceptions of them and, by implication, the people who ride on them, having dismissed them as being rides designed for people who think cycling is the new golf and are happy to pay £20+ to ride on public roads, etc.
But I have to say I really enjoyed it - more than I expected to. It was a very pretty route, mostly quiet roads and great weather helped. When I got to the start, at Chichester College, I was struck by the scale of it. There were between three and four hundred people and bikes. But the organisation seemed to cope with this as there were no significant queues either to sign in, or to start.
I rode sometimes on my own, at other times with other single riders or smaller groups and at one point jumped on the back of a fast club train with about 8 riders. I enjoyed the banter with people I met and it was a friendly atmosphere.
In terms of value for money, the cost was (I think) £24. For that I got a very smoothly organised event, very efficient signs making it almost impossible to lose the route, plenty of food and drink (the street value of the energy bars I got given was probably at least half of my entry fee!) at roadside stops and the chance to have a shower before I drove home, which was a good bonus. There was also the insurance which, as a member of CTC, two clubs and AUK, I didn't feel I really needed.
I wouldn't do loads of them, but I might do another now and again.
For lots of people, they are what cycling is about. I think part of the appeal is that they are user friendly and accessible. Audax can be a bit harder to work out what is going on and many people find clubs intimidating. The growth of them has shown that there is more of a market for £20+ rides than people ever thought, but if you think they are a rip-off, you are probably not in the target segment.