I think it is similar to the diet meal replacement used in the Newcastle Study, and the common ones such as Slimfast and the supermarket own brands.
These seem O.K. for a targeted short term radical weight loss campaign but you have to also be prepared to revise your eating habits long term or any weight you take off will go straight back on again.
Some of these meal replacements are quite sugar and carb heavy in their formulation but if you use them as directed the total sugars and carbs in the day are still quite low.
Hope this helps.
LGC