I've done Slim and Save, which is a much cheaper version of a VLCD- similar prices to Exante. I lost 4.5 stone last year on it- great! But I put a lot of it back on with terrible eating after. I know where I went wrong, I'm just starting it again and this time hopefully will have better self control. All the gain was down to me, not the diet.
Although you don't get counseling or anything on S&S I found the company great to deal with, you have a question and they'll get back to right away, plus they have a support part for re-feeding after which I wish I'd done.
You do see results much, much quicker on a VLCD than a regular diet, n average you can lose a stone a month. The first week is a bigger loss, usually around 7lb, but that's your water weight. I found it easyish going after the first few days. I've never had bad ketone breath or got spotty. In fact my skin and hair was much clearer!
You do have to be really strict on a VLCD or it doesn't work. No food unless it's allowed- that's why I liked S&S, you could have 4 packs a day (shakes, soups, meals, bars) or 3 plus 100g chicken/tuna. Plus some veg from a list. I sound like a blinking advert, but it worked for me. And hopefully will again!