Slim-Fast has the nutrients in it (like a vitamin does) but there are different sources of protein-and some meal replacements use "cheaper" sources of protein. Does that make sense? Adding fiber powder to the meal replacement shakes is fiber...but it is also not as good for you as getting the fiber naturally from whole grains, fruits, and veggies.
It is better than nothing-I agree with that. And I do like the fact that they have started the Optima series with less sugar. (their original line was LOADED with sugar)