I have different, mixed opinions on products like SlimFast...
I think that it is fine to use a meal replacement bar or shake on days when you are in a hurry and can't eat a real meal. I am a dancer and imports vendor-and there are days where I attend a dance workshop all day long-say 3 hours in the morning of dancing-then I have to stay and vend (hip scarves, veils, etc.) during the "breaks" and then right back to 2-3 more hours of dancing in the afternoon. I have to pack a meal bar, bottled water, and some easy to pack produce like baby carrots or an apple in my bag-because if I don't-then I don't eat. It is that simple.
I don't think that you should really use meal replacements for 2 meals a day-every single day-on a plan.
On the positive side-Slim-Fast has recently changed over their shakes and bars to a new formulation with less sugar. That was a long time coming. I actually test marketed these new products for them a couple months ago. Also-as far as learning to eat "healthfully" again after losing your desired weight-SF does have this information on their website...but you have to read it.
I think that is the catch with ANY plan-not just Slim Fast. I know many people who have gained all their weight back after stopping Slim Fast, Atkins, calorie counting, or whatever they were doing-because they simply went back to eating the same way that made them fat in the first place. They whole reason that SF works is because you are reducing calories-plain and simple. The same thing would happen if you were eating 220 calories for breakfast and lunch, fruit for snacks, and the lean meat/salad dinner. It is the calories that count, and the calories that make SF work.
Slim Fast can work-any plan can work if you stick with it-but most people complain of not getting full or satisfied from shakes. (Maybe the meal bars, soups, etc. that they offer would be better for these people.)
Personally-I rarely use SF for meal replacements. I use a meal replacement for about 3 meals per week (instead of 14!) but when I do-I choose other options such as EAS, Myoplex, or a Clif Bar or Bakers Breakfast Cookie.
I would recommend to SF users that you switch over to the newer less sugar formula (Optima) just because it is less sugar-which is better for everyone.