There are some good meal replacements out there, I use one which works well for me, but as mentioned you need to look at the ingredients. In my opinion Whey Protein is superior to other forms of proteins but it needs to be in its pure, undenatured form - if its been heat or acid treated it will be dead and the amino acid profile will not be as strong.

Look for a product which contains a balance of protein, carbs and other essential minerals (often lacking in our diets)