I'm not on Cambridge, I'm on a different VLCD and so far it is really, really helping. I'm on week 6 and have lost 1st 9lb so far, I have quite a way to go though. I'm learning portion control, that I can exist on a small portion and I have really seen the light on low-carbing! VLCDs are low carb, low fat and high protein. I'm rarely hungry, have energy, I can cook for the kids without nibbling their stuff! Plus I love all the packs on this diet, meals, soups, bars and shakes all lovely.
It's cheaper than CD but you don't get the councellor or anything like that, you buy it online so I get all my support on minimins. VLCDs are for some people and not for others, just like SW and WW and atkins etc. Some people coudn't do what I'm doing, plenty of people are doing it right now!
I have made sure I have a solid plan in place for when I get close to goal- I'm aiming to low carb as a long-term plan, not a diet as such but sticking to the principles of high protein low carb. Have yet to decide whether to go with a maintence plan like that offered with atkins or something else but I'm constantly researching.
There is always a risk of gaining everything back after, as there is on any diet. If you go back to the same way of eating- of course you will gain, all and more, because the person who started the diet was a lot bigger than at the end so eating the same as you used to will be a lot worse than before!