A person following the low GI diet plan could eat a meal of low glycemic index foods and still come out worse for it according to the plan because other factors have not been taken into account.
For instance, fats in a meal slow down digestion, therefore possibly changing the effect on the body. They also help you to feel full.
There is more to research needed before this diet is proven to increase weight loss or make a difference in weight loss at all.
It is good to eat foods that provide stable energy all day, but an entire meal plan of them may not be what you are looking for.
Right now, there is too much variance in the numbers depending on who you ask.  A low fat plan would be easier to follow with better results.
The plan does emphasize foods with a lot of water in them, such as fruits and veggies. Look at the calories as well as the GI and you might be onto a sensible eating plan that will not spike your blood sugar, and thus your food cravings.